HANDBOOK 
ON  OVERHEAD 

LINE  CONSTRUCTION 


HANDBOOK  ON  OVERHEAD 
LINE  CONSTRUCTION 


COMPILED   BY  THE 

SUB-COMMITTEE    ON    OVERHEAD    LINE    CONSTRUCTION 
NATIONAL  ELECTRIC  LIGHT  ASSOCIATION 


Sub-Committee 

THOMAS  SPROULE,  Chairman 

PAUL  SPENCER  R.  D.  COOMBS  W.  T.  OVIATT 

FARLEY  OSGOOD  J.  E.  KEARNS 

N.  '•£.  ^UNK,  Secretary 


PRESENTED  AT  THE  THIRTY-SEVENTH  CONVENTION 
NATIONAL  ELECTRIC  LIGHT  ASSOCIATION 
HELD  AT  PHILADELPHIA,  PENNSYLVANIA 

JUNE  1-5,  1914 


VA3 


Copyright,  1914 
National  Electric  Light  Association 


FRANKLIN  PRINTING  COMPANY 
PHILADELPHIA 


PUBLISHED  BY  ORDER  OF  THE 

National  Electric  Light  Association 

NEW  YORK  CITY 


OFFICERS 


JOSEPH   B.  McCALL 

President 
Philadelphia,  Pa. 


JOHN  A.  BRITTON 

Vice  President,  San  Francisco,  Cal. 
HOLTON  H.  SCOTT 

Vice  President,  New  York 
E.  W.  LLOYD 

Vice  President,  Chicago,  111. 
E.  C.  DEAL 

Vice  President,  Augusta,  Ga. 
T.  COMMERFORD  MARTIN 

Secretary,  New  York 


S.  A.  SEW  ALL 

Assistant  to  Secretary,  New  York 
W.  F.  WELLS 

Treasurer,  Brooklyn,  N.  Y. 
H.  BILLINGS 

Asst.  Sec'y  and  Treas.,  New  York 
EVERETT  W.  BURDETT 

General  Counsel,  Boston,  Mass. 
GEORGE  W.  ELLIOTT 

Master  of  Transp'tion,  New  York 


EXECUTIVE  COMMITTEE 


JOSEPH  B.  McCALL 


H.  C.  ABELL 
HENRY  G.  BRADLEE 
JOHN  A.  BRITTON 
E.  C.  DEAL 
CHARLES  L.  EDGAR 
W.  C.  L.  EGLIN 
A.  C.  EINSTEIN 
H.  L.  BLEECKER 

President  Northwest  Association 
DUNCAN  T.  CAMPBELL 

President  Pennsylvania  Section 
R.  E.  LEE 

President  Iowa  Electrical  Association 
W.  F.  GORENFLO 

President  Mississippi  Section 
H.  A.  HOLDREGE 

President  Nebraska  Section 
H.  W.  PECK 

President  Eastern  New  York  Section 


C.  E.  GROESBECK 
E.  W.  LLOYD 
R.  S.  ORR 
W.  N.  RYERSON 
HOLTON  H.  SCOTT 
FRANK  M.  TAIT 
ARTHUR  WILLIAMS 
T.  W.  PETERS     . 

President  Southeastern  Section 

C.  W.  ROGERS 

President  New  Hampshire  Section 
H.  C.  STERLING 

President  Michigan  Section 

D.  R.  STREET 

President  Canadian  Association 
C.  C.  WELLS 

President  New  England  Section 
W.  W.  FREEMAN 

Chairman  Hydro- Electric  Section 


T.  I.  JONES,  Chairman  Commercial  Section 

297667 


TABLE  OF  CONTENTS 


Section  Page 

1.  An  Abridged  Dictionary  of  Electrical  Words,  Terms  and 

Phrases 1 

Logarithmic  Tables,  Trigonometric  Tables.  Deci- 
mal Equivalent  Tables,  Tables  of  Circumferences 
and  Areas  of  Circles,  Units  and  Conversion 
Tables. 

2.  Distribution  and  Transmission  Line  Supports 107 

3.  Conductors  and  Wire  Tables 171 

4.  Cross- Arms,  Pins  and  Pole  Line  Hardware 263 

5.  Insulators 285 

6.  Transformers  and  Induction  Regulators.     Lightning  Phe- 

nomena in  Connection  with  Electric  Circuits,  Protective 
Apparatus,  Grounding,  Etc 315 

7.  Systems  of  Distribution  and  Transmission,  Electrical  Cal- 

culations   'j 435 

8.  Mechanical  Calculations  of  Transmission  and  Distribution 

Lines '. 519 

9.  Preservative  Treatment  of  Poles  and  Cross- Arms 561 

1  0.  Primary  and  Secondary  Line  Construction *. 675 

1.1.  Meteorological  Data,   General  Data  and  Rules  for  Re- 
suscitation from  Electric  Shock . .  .  750 


Preface 

THE  purpose  of  this  Handbook  is  the  presentation,  in 
one  volume,  of  descriptions  of  the  methods  and  the 
materials  employed  in  overhead  line  construction, 
and  a  tabulation  of  the^necessary  formulae  for  the  electrical 
and  mechanical  solutions  of  various  transmission  and 
distribution  problems. 

While  many  handbooks  hitherto  have  been  prepared 
covering  these  various  branches  of  engineering,  this,  we 
believe,  is  the  first  attempt  made  to  compile  a  work 
strictly  on  overhead  line  construction. 

Literature  on  the  subject  is  comparatively  scarce  and 
that  which  is  available  is  distributed  through  a  great 
number  of  publications.  It  has  therefore  been  felt  by 
almost  all  who  have  taken  an  active  interest  in  overhead 
line  construction  that  a  handbook  would  be  extremely 
useful.  The  preparation  of  this  book  has  involved  the 
collection  of  the  available  data  and  selection  from  these 
data  what  were  most  essential. 

It  is  not  the  intention,  and  it  must  not  be  so  considered, 
that  this  is  a  handbook  of  rules  and  regulations ;  or  that 
an  attempt  has  been  made  to  create  standards  or  write 
specifications.  It  is  rather  a  collection  of  useful  informa- 
tion, which  should  prove  of  material  assistance  to  all  those 
engaged  in  the  construction  or  maintenance  of  overhead 
lines  for  light  and  power  purposes.  The  authorship  of 
such  specifications  as  have  been  included  is  specially  noted. 
The  formulae  used  have  been  taken  from  authoritative 
sources,  and  while  the  Sub-Committee  is  not  responsible 
for  them,  it  believes  they  will  be  found  of  service. 

It  must  be  expected  there  will  be  found  omissions  of 
matter  which  should  have  been  added;  and  material  may 
be  included  which  later  may  prove  of  little  value.  It  is 


Preface 

hoped,  however,  that  users  of  this  Handbook  will  assist 
future  committees  by  offering  suggestions,  additions  or 
corrections  for  use  in  later  editions. 

In  the  treatment  of  apparatus,  efforts  have  been  made 
to  describe  the  various  types  at  present  on  the  market. 
It  has  been  necessary  to  quote  extensively  from  manu- 
facturers' literature;  and,  in  illustrating  types  of  devices, 
to  select  those  marketed  by  a  limited  number  of  manu- 
facturers. This  is  not  intended  either  as  an  endorsement 
of  such  apparatus,  or  as  a  condemnation  of  apparatus 
not  illustrated  or  described.  In  the  majority  of  cases, 
selections  were  made  because  of  the  availability  of  the 
information. 

The  compilation  of  the  data  for  this  Handbook  has  been 
carried  out  by  the  secretary  of  the  Sub-Committee, 
Mr.  N.  E.  Funk,  of  The  Philadelphia  Electric  Company, 
to  whom  belongs  the  greatest  share  of  credit  for  what  has 
been  accomplished  in  the  preparation  of  this  work. 
Mr.  Funk  was  detailed  by  that  Company  to  devote  all  of 
his  time  to  this  subject,  under  the  direction  of  the  Chairman 
of  the  Sub-Committee,  who  desires  to  take  this  opportunity 
to  express  his  appreciation  of  the  amount  of  thought  and 
judgment  given  to  the  work. 

We  also  wish  to  acknowledge  the  assistance  which  we 
have  received  wherever  asked,  and  especially  to  Professor 
Charles  F.  Marvin,  Chief,  Professor  William  J.  Humphreys 
and  Mr.  George  S.  Bliss,  all  of  the  United  States  Weather 
Bureau,  who  have  cooperated  in  the  compilation  of  the 
chapter  on  " Meteorology,"  which  is  the  first  attempt  ever 
made  to  tabulate  such  data  for  publication  in  a  handbook. 

The  Section  on  the  "Preservative  Treatment  of  Poles 
and  Cross-Arms"  is  a  reprint  of  the  1910  and  1911  Re- 
ports of  the  National  Electric  Light  Association  Committee 
appointed  to  consider  this  subject.  These  reports  have 
viii 


Preface 

been  combined  by  Mr.  W.  K.  Vanderpoel,  of  the  Public 
Service  Electric  Company,  whose  efforts^  are  gratefully 
acknowledged. 

The  available  information  on  "Pole  Timber  Logging 
and  Pole  Timber  Defects"  is  meager;  much  of  the  data 
that  are  included  has  been  secured  through  the  coopera- 
tion of  Mr.  O.  T.  Swan,  of  the  Forestry  Service,  U.  S. 
Bureau  of  Agriculture,  and  Mr.  F.  L.  Rhodes,  of  the 
American  Telephone  and  Telegraph  Company,  and  this 
also  is  gratefully  acknowledged. 

The  ready  cooperation  of  the  various  manufacturers, 
who  contributed  for  publication  much  valuable  information 
many  photographs  and  cuts,  is  hereby  acknowledged. 

Grateful  acknowledgment  is  also  made  particularly  to 
Mr.  J.  C.  Parker,  of  the  Rochester  Railway  and  Light 
Company  Mr  F  L  Rhodes  of  the  American  Telephone 
and  Telegraph  Company,  Mr.  S.  M.  Viele,  of  the  Pennsyl- 
vania Railroad  Company,  Mr.  J.  E.  Kearns,  of  the  General 
Electric  Company,  Mr.  R.  D.  Coombs,  of  R.  D.  Coombs 
and  Company,  Mr.  E.  G.  Reed,  of  the  Westinghouse 
Electric  Company  and  also  to  Mr.  W.  C.  L.  Eglin,  Mr. 
George  Ross  Green,  Mr.  Horace  P.  Liversidge,  Mr.  Charles 
Penrose,  Mr.  J.  V.  Matthews,  Mr.  W.  L.  Robertson, 
Mr.  Alexander  Wilson,  3rd  and  Mr.  Robert  A.  Hentz, 
all  of  The  Philadelphia  Electric  Company;  and  to  rep- 
resentatives of  the  many  manufacturing  companies  for 
their  assistance  in  checking  over  the  various  parts  of  the 
Handbook. 

In  the  first  edition  of  any  handbook  embracing  so  large 
a  subject,  errors  undoubtedly  will  be  made.  These  will 
be  corrected  in  future  editions  and  we  would  ask  our 
readers  to  send  all  criticisms  to  the  secretary  of  the  Asso- 
ciation so  that  they  can  be  referred  to  those  responsible 
for  the  revision  of  the  Handbook.  In  this  connection, 


Preface 

consideration  should  be  given  to  the  broadening  of  the 
scope  of  the  Handbook,  and  to  the  question  as  to  whether 
it  should  include  transmission  line  construction,  under- 
ground construction,  maintenance  and  methods  of  keeping 
accurate  records  of  outdoor  apparatus,  etc.  These  and 
other  important  questions  must  receive  the  attention  of 
future  committees,  and  it  will  be  extremely  helpful  to 
these  committees  to  obtain  the  advice  and  assistance  of 
the  membership  at  large. 

In  conclusion,  we  desire  to  express  our  appreciation  to 
the  present  officers  and  Executive  Committee  of  the 
National  Electric  Light  Association,  particularly  to  its 
president,  Mr.  Joseph  B.  McCall,  through  whose  personal 
efforts  the  preparation  and  publication  of  the  Handbook 
have  been  made  possible. 

It  is  our  earnest  hope  that  this  Handbook  may  prove 
of  service  to  the  industry;  this  has  been  the  controlling 
thought  throughout  its  preparation. 

SUB-COMMITTEE  ON  HANDBOOK 

THOMAS  SPROULE,  Chairman 


PHILADELPHIA,  JUNE  1 ,  1914 

X 


SECTION  1 

AN  ABRIDGED  DICTIONARY  OF  ELECTRICAL 
WORDS,  TERMS  AND  PHRASES 


TABLES 

INCLUDING  LOGARITHMIC  TABLES,  TRIGONO- 
METRIC   TABLES,    DECIMAL   EQUIVALENT 
TABLES,  TABLES  OF  CIRCUMFERENCES 
AND   AREAS   OF   CIRCLES,   UNITS 
AND   CONVERSION  TABLES 


A. 

A.  C.    An  abbreviation  for  alternating  current. 

ABSOLUTE  TEMPERATURE.  That  temperature  which  is 
reckoned  from  the  absolute  zero,  -273°  C.  or  -459°  F. 

ADMITTANCE.  The  reciprocal  of  the  impedance  in  an  alter- 
nating-current circuit.  The  apparent  conductance  of  an  alternating- 
current  circuit  or  conductor. 

AERIAL  CABLE.  An  insulated  cable  protected  by  a  metallic 
sheath  and  suspended  from  a  messenger  cable  which  is  usually 
grounded. 

AERIAL  CONDUCTOR.     An  overhead  conductor. 

AGEING  OF  TRANSFORMER  CORE.  Increase  in  the  hys- 
teretic  coefficient  in  the  iron  of  a  transformer  core  during  its  com- 
mercial operation,  from  its  continued  magnetic  reversals  at  com- 
paratively high  temperature. 

AIR-CORE  TRANSFORMER.  A  transformer  which  is  void  of 
a  core  other  than  that  of  air. 

AIR-GAP.  In  a  magnetic  circuit,  any  gap  or  opening  containing 
air  only. 

AIR-PATH.  The  path  a  disruptive  discharge  takes  through  the 
air. 

AIR-RELUCTANCE.  The  reluctance  of  that  portion  of  a  mag- 
netic circuit  which  consists  of  air. 

ALTERNATION.  An  oscillation  of  an  electric  or  magnetic  wave 
from  a  zero  to  a  maximum  value  and  back  to  zero  again,  a  half  of  a 
cycle.  (See  cycle.) 

ALTERNATING  CURRENT  is  a  current  which  alternates  regu- 
larly in  direction.  Unless  distinctly  otherwise  specified,  the  term 
"alternating  current"  refers  to  a  periodic  current  with  successive 
half  waves  of  the  same  shape  and  area. 

An  alternating  current  equals  the  electromotive  force  divided  by 
the  impedance,  or 

E  E 


z      VR2+X2 
E 


1  = 


This  expression  may  be  solved  by  complex  quantities  or  vectorially. 

I  3] 

I 


Sec.  1       :*    *          V    :  tirCTlONARY 


-(-A) 


Z  =»*.  vRM-  XS,  Impedance  01  circuit 
R=   '  'Ohmic  resistance 'of  circuit 

X  =       Reactance  of  circuit  in  Ohms  =  (  &L  —  -^ 

L  =  Coefficient  of  self-induction  in  henrys 

C  =  Capacity  of  the  circuit  in  farads 

6>  =  27rf,  angular  velocity,  where 

f   =  the  number  of  cycles  per  second  or  frequency. 

ALTERNATING  CURRENT  POWER.  The  power  expended  in 
an  alternating  current  circuit  at  any  given  instant  in  the  cycle  is 
equal  to  the  product  of  the  voltage  and  current  at  that  instant. 
When  the  voltage  and  current  reverse  at  the  same  instant,  this 
product  is  always  positive,  and  if  their  wave  forms  are  alike,  the 
power  expended  is  a  maximum,  and  is  equal  to  the  product  of  the 
effective  values  of  voltage  and  current.  Such  voltages  and  currents 
are  in  phase.  When  the  term  "power  expended  in  an  alternating 
current  circuit"  is  used,  the  average  value  during  one  cycle  is  ordi- 
narily meant. 

ALTERNATION,  PERIODICITY  OF.  The  time  required  for 
the  current  to  pass  through  one  cycle.  When  any  particular  periodic- 
ity or  frequency  is  spoken  of,  as  for  example,  250  alternations  per 
second,  125  complete  periods  or  cycles  per  second  are  meant. 

ALUMINUM.  A  soft,  ductile,  malleable  metal  of  white  color 
approaching  silver,  but  with  a  bluish  cast.  Does  not  readily 
oxidize.  Melts  at  a  low  temperature.  Cannot  readily  be  welded, 
or  brazed  or  soldered.  Very  electro-positive,  and  is  eaten  away  in 
presence  of  salts  and  other  metals.  Atomic  weight  27.1.  Specific 
gravity  2.6  to  2.7.  The  lightest  of  all  useful  metalc  next  to  mag- 
nesium. Expands  greatly  with  increasing  temperature.  For  equal 
conductivity,  aluminum  has  about  one-half  the  weight  of  copper. 
Tenacity  about  one-third  that  of  wrought-iron. 

AMERICAN  WIRE  GAUGE.  The  name  generally  given  to  the 
Brown  and  Sharpe  wire  gauge,  in  which  the  large  wire  No.  0000,  has 
a  diameter  of  0.46",  the  wire  No.  36,  0.005",  and  all  other  diameters 
are  in  geometrical  progression. 

It  will  be  seen  upon  examining  a  wire  table  that  an  increase  of 
three  in  the  wire  number  corresponds  to  doubling  the  resistance  and 
halving  the  cross-section  and  weight.  Also,  that  an  increase  of 
ten  in  the  wire  number  increases  the  resistance  ten  times  and  di- 
minishes the  cross-section  and  weight  to  one-tenth  their  original 
values. 

The  American  Steel  and  Wire  gauge  is  used  almost  universally 
in  this  country  for  steel  and  iron  wires. 

The  Birmingham  gauge  is  used  largely  in  England  as  their  stand- 
ard, and  in  this  country  for  steel  wires  and  for  other  wires  not  used 
especially  for  electrical  purposes. 

[4] 


DICTIONARY  Sec.  1 

AMPERE.  The  practical  unit  of  electric  current.  A  rate  of 
flow  of  electricity  transmitting  one  coulomb  per  second.  The 
current  of  electricity  which  would  pass  through  a  circuit  whose 
resistance  is  one  ohm,  under  an  electromotive  force  of  one  volt. 
A  current  of  such  a  strength  as  will  deposit  1.118  milligrammes  of 
silver  per  second  from  a  specifically  prepared  solution  of  silver 
nitrate. 

The  value  of  the  ampere  as  adopted  by  the  International  Congress 
of  1893,  at  Chicago  is  equal  to  the  one-tenth  of  a  unit  of  current  in 
the  C.G.S.  system  of  electric-magnetic  units  and  represented  with 
sufficient  accuracy  for  practical  purposes,  by  the  unvarying  current, 
which,  when  passed  through  a  solution  of  nitrate  of  silver  in  water, 
in  accordance  with  certain  specifications,  deposits  silver  at  the  rate 
of  0.001118  of  a  gramme-per-second. 

AMPERE  HOUR.  A  unit  of  electrical  quantity  equal  to  the 
quantity  of  electricity  conveyed  by  one  ampere  flowing  for  one  hour. 
A  quantity  of  electricity  equal  to  3600  coulombs. 

AMPERE  SECOND.  A  unit  of  electric  quantity  equal  to  the 
quantity  of  electricity  conveyed  by  one  ampere  flowing  for  one 
second.  A  coulomb. 

AMPERE  TURN.  A  unit  of  magneto-motive  force  equal  to  that 
produced  by  one  ampere  flowing  around  a  single  turn  of  wire. 

AMPLITUDE  OF  VIBRATION  OF  WAVE.  The  extent  of  a 
movement  measured  from  the  starting  point  or  position  of  equilib- 
rium. The  maximum  voltage  of  a  sine  wave. 

ANCHOR  LOG.  A  log  buried  in  the  ground  and  serving 
as  an  anchor  for  a  pole  guy. 

ANGLE  OF  LAG  OR  LEAD  OF  CURRENT.  An  angle  whose 
tangent  is  equal  to  the  ratio  of  the  reactive  to  the  ohmic  resistance 
in  a  circuit;  whose  cosine  is  equal  to  the  ohmic  resistance  divided  by 
the  impedance  of  a  circuit;  whose  cosine  is  the  ratio  of  the  real  to 
the  apparent  power  in  an  alternating  current  circuit  or  the  angle  by 
which  the  current  lags  behind  or  leads  the  e.m.f. 

ANGULAR  VELOCITY.  The  velocity  of  a  point  moving  rel- 
atively to  a  centre  of  rotation  or  to  some  selected  point,  and  usually 
measured  in  degrees  per  second,  or  in  radians  per  second.  In  a 
sinusoidal  current  circuit  the  product  of  6.2832  and  the  frequency 
of  the  current. 

APPARENT  EFFICIENCY.  The  volt-ampere  efficiency  or  the 
ratio  of  volt-ampere  output  to  volt-ampere  input.  In  apparatus  in 
which  a  phase  displacement  is  inherent  to  their  operation,  apparent 
efficiency  should  be  understood  as  the  ratio  of  net  power  output  to 
volt-ampere  input. 

APPARENT  POWER.  In  an  alternating  current  circuit  the 
product  obtained  by  multiplying  the  mean  effective  value  of  the 

[5] 


Sec.  1  DICTIONARY 

e.m.f .  by  the  mean  effective  value  of  the  current,  such  as  read  directly 
from  a  volt-meter  and  ammeter. 

p 7T— — =  apparent  power.     When  the  power-factor  is  unity 

the  apparent  power  in  volt-amperes  is  equal  to  watts. 

APPARENT  OR  EQUIVALENT  RESISTANCE.  Represents  a 
counter  e.m.f.  which  is  in  exact  phase  opposition  with  the  current, 
i.  e.,  in  phase  with  the  I  R  drop.  These  counter  e.m.f. 's  may  be 
generated  in  motors  or  in  transformers.  Losses  in  the  magnetic 
circuit  such  as  hysteresis  and  secondary  losses  such  as  eddy  currents 
may  also  be  considered  as  forming  part  of  the  apparent  resistance 
loss. 

ARMOR  OF  CABLE.  The  protecting  sheathing  or  metallic 
covering  of  a  submarine  or  other  electric  cable. 

ASBESTOS.  A  hydrous  silicate  of  magnesia,  i.  e.,  silicate  of 
magnesia  combined  with  water.  A  fire-proofing  material  some- 
times used  by  itself  or  in  connection  with  other  material  for  insulating 
purposes. 

AUTOMATIC  CIRCUIT-BREAKER.  A  device  for  automatically 
opening  a  circuit  when  the  current  passing  through  it  is  excessive. 

AUTOMATIC  SWITCH.  A  switch  which  is  automatically 
opened  or  closed  on  the  occurrence  of  certain  predetermined  events. 

AUTO-TRANSFORMER.  A  one-coil  transformer  consisting  of 
a  choking  coil  connected  across  a  pair  of  alternating-current  mains, 
and  so  arranged  that  a  current  or  pressure  differing  from  that 
supplied  by  the  mains  can  be  obtained  from  it  by  tapping  the  coil 
at  different  points.  Called  also  a  compensator.  A  transformer  in 
which  a  part  of  the  primary  winding  is  used  as  the  secondary  wind- 
ing, or  conversely. 

AXIS  OF  CO-ORDINATES.  A  vertical  and  a  horizontal  line, 
usually  intersecting  each  other  at  right  angles,  and  called  respectively 
the  axes  of  ordinates  and  abscissas,  from  which  the  ordinates  and 
abscissas  are  measured. 

B. 

B.  &  S.  G.  An  abbreviation  for  Brown  and  Sharpe's  Wire 
Gauge. 

B.  W.  G.     An  abbreviation  for  Birmingham  Wire  Gauge. 

BALANCED  CIRCUIT.  A  circuit  which  has  been  so  erected  and 
adjusted  as  to  be  free  from  mutual  inductive  disturbances  from 
neighboring  circuits. 

BALANCED  LOAD  O¥  SYSTEM.  Any  system  is  said  to  be 
balanced  when  all  conditions  of  each  of  the  circuits  of  a  polyphase,  or 
n-wire,  system  are  alike  and  numerically  equal. 

[6] 


DICTIONARY  Sec.  1 

BARROW-REEL.  A  reel  supported  on  a  barrow  for  convenience 
in  paying  out  an  overhead  conductor  during  its  installation. 

BEG-OHMS.  One  billion  ohms,  or  one  thousand  megohms. 
BICRO.  A  prefix  for  one-billionth,  one  thousand  millionth. 
BIGHT  OF  CABLE.  A  single  loop  or  bend  of  cable. 

BIMETALLIC  WIRE.  A  compound  wire  consisting  of  a  steel 
core  and  a  copper  envelope. 

BLOWING  A  FUSE.  The  fusion  or  volatilization  of  a  fuse  wire 
or  safety  strip  by  the  current  passing  through  it. 

BLOWING  POINT  OF  FUSE.  The  current  strength  at  which  a 
fuse  blows  or  melts. 

BRAIDED  WIRE.  A  wire  covered  with  a  braiding  of  insulating 
material. 

BRANCH  CIRCUITS.  Additional  circuits  provided  at  points 
of  a  circuit  where  the  current  branches  or  divides,  part  of  the  current 
flowing  through  the  branch,  and  the  remainder  flowing  through  the 
original  circuit.  A  shunt  circuit. 

BRANCH  CUT-OUT.  A  safety  fuse  or  cut-out,  inserted  between 
a  pair  of  branch  wires  and  the  mains  supplying  them. 

BREAKING  DOWN  OF  INSULATION.  The  failure  of  an 
insulating  material,  as  evidenced  by  the  disruptive  passage  of  an 
electric  discharge  through  it. 

BRITANNIA  JOINT.  A  joint  in  which  the  ends  of  the  wires  are 
laid  side  by  side  bound  together,  and  subsequently  soldered. 

BRONZE.     An  alloy  of  copper  and  tin. 

BRUSH  AND  SPRAY  DISCHARGE.  A  streaming  form  of  high 
potential  discharge  possessing  the  appearance  of  a  spray  of  silvery 
white  sparks,  or  of  a  branch  of  thin  silvery  sheets  around  a  powerful 
brush.  Obtained  by  increasing  the  frequency  of  the  alternations. 

BRUSH  DISCHARGE.  The  faintly  luminous  discharge  which 
takes  place  from  a  positive  charged  pointed  conductor. 

BUNCHED  CABLE.  A  cable  containing  more  than  a  single  wire 
or  conductor. 

c. 

C.    An  abbreviation  for  Centigrade. 

C.    A  symbol  used  for  capacity.     Farad. 

The  defining  equation  is  C  =  -^~ 

hi 

The  same  symbol  is  often  used  for  current. 

[7] 


Sec.  1  DICTIONARY 

c.c.  An  abbreviation  for  cubic  centimeter,  the  C.G.S.  unit  of 
volume. 

cm.     An  abbreviation  for  centimeter,  the  C.G.S.  unit  of  length. 

C.  G.  S.  UNITS.  An  abbreviation  for  centimeter,  gram,  second 
units.  The  metric  system  of  units  for  measuring  length,  mass  and 
time. 

CABLE.  A  stranded  conductor  (single-conductor  cable);  or 
a  combination  of  conductors  insulated  from  one  another  (multiple- 
conductor  cable). 

CABLE  CASING.     The  metallic  sheathing  of  a  cable. 

CABLE  CORE.  The  hemp  or  steel  center  of  an  aerial  electrical 
cable  to  enlarge  the  cross  section  of  the  cable  or  to  carry  the  me- 
chanical strain  of  the  conductors. 

CABLE  DUPLEX.  Two  insulated  single-conductor  cables  twisted 
together. 

CABLE  GRIP.  The  grip  provided  for  holding  the  end  of  an  under- 
ground cable  while  it  is  being  drawn  into  a  duct. 

CABLE  HOUSE.  A  hut  provided  for  securing  and  protecting 
the  end  of  a  cable. 

CABLE,  SUBMARINE.     A  cable  designed  for  use  under  water. 

CABLE  VAULT.  A  vault  provided  in  a  building  where  cables 
enter  from  underground  conduits  and  where  the  cables  are  opened 
and  connected  to  fusible  plugs  or  safety  catches. 

CALORIE.  A  heat  unit.  The  quantity  of  heat  required  to  raise 
1  gramme  of  water  1°  centigrade. 

CAP  WIRE.  An  overhead  wire  carried  on  the  summit  of  a  pole, 
as  distinguished  from  an  overhead  wire  carried  on  a  crossarm. 

CAPACITY,  ELECTROSTATIC.  The  quantity  of  electricity 
which  must  be  imparted  to  a  given  body  or  conductor  as  a  charge, 
in  order  to  raise  its  potential  a  certain  amount.  (See  Potential 
Electric.) 

The  electrostatic  capacity  of  a  conductor  is  not  unlike  the  capa- 
city of  a  vessel  filled  with  a  liquid  or  gas.  A  certain  quantity  of 
liquid  will  fill  a  given  vessel  to  a  level  dependent  on  the  size  or 
capacity  of  the  vessel.  In  the  same  manner  a  given  quantity  of 
electricity  will  produce,  in  a  conductor  or  condenser  a  certain  dif- 
ference of  electric  level,  or  difference  of  potential,  dependent  on  the 
electrical  capacity  of  the  conductor  or  condenser. 

In  the  same  manner,  the  smaller  the  capacity  of  a  conductor,  the 
smaller  is  the  charge  required  to  raise  it  to  a  given  potential,  or  the 
higher  the  potential  a  given  charge  will  raise  it. 

The  capacity  C,  of  a  conductor  or  condenser,  is  therefore  directly 
proportional  to  the  charge  Q,  and  inversely  proportional  to  the 
potential  E;  or, 

[8] 


DICTIONARY  Sec.  1 

C_Q 
C-~E~ 

from  which  we  obtain  Q  =CE. 

The  quantity  of  electricity  required  to  charge  a  conductor  or 
condenser  to  a  given  potential  is  equal  to  the  capacity  of  the  con- 
ductor or  condenser  multiplied  by  the  potential  through  which  it  is 
raised. 

CAPACITY,  ELECTROSTATIC,  UNIT  OF.  The  farad.  Such  a 
capacity  of  a  conductor  or  condenser  that  an  electromotive  force 
of  one  volt  will  charge  it  with  a  quantity  of  electricity  equal  to  one 
coulomb. 

CAPACITY  OF  CABLE.  The  quantity  of  electricity  required  to 
raise  a  given  length  of  cable  to  a  given  potential,  divided  by  the 
potential.  The  ability  of  a  conducting  wire  or  cable  to  permit  a 
certain  quantity  of  electricity  to  be  passed  into  it  before  acquiring 
a  certain  potential. 

CAPACITY  OF  LINE.  The  ability  of  a  line  to  act  as  a  condenser, 
and,  therefore,  like  it,  to  possess  capacity. 

CAPACITY  REACTANCE.  The  property  by  which  a  counter 
e.m.f.  is  produced  when  an  e.m.f.  is  impressed  across  the  terminals 
of  two  conducting  surfaces  separated  by  a  dielectric. 

CARBON.  An  elementary  substance  which  occurs  naturally  in 
three  distinct  allotropic  forms:  graphite,  charcoal  and  the  diamond. 

CARRYING  CAPACITY.  The  maximum  current  strength  that 
any  conductor  can  safely  transmit. 

CATENARY  CURVE.  The  curve  described  by  the  sagging  of  a 
wire,  under  its  own  weight,  when  stretched  between  two  points  of 
support. 

CENTIGRAMME.  The  hundredth  of  a  gramme;  or,  0.1543 
grain  avoirdupois. 

CENTIMETER.    The  hundredth  of  a  metre;  or  0.3937  inch. 

CENTIMETER-GRAMME-SECOND  SYSTEM.  A  system 
based  on  the  centimeter  as  the  unit  length,  the  gramme  as  the  unit 
of  mass,  and  the  second  as  the  unit  of  time. 

CENTER  OF  DISTRIBUTION.  Is  the  point  from  which  the 
electrical  energy  must  be  supplied  to  use  a  minimum  weight  of 
conducting  material. 

CHARACTERISTIC  CURVE.  A  diagram  in  which  a  curve  is 
employed  to  represent  the  relation  of  certain  varying  values.  A 
curve  indicating  the  characteristic  properties  of  a  dynamo-electric 
machine  under  various  phases  of  operation.  A  curve  indicating 
the  electromotive  force  of  a  generator,  as  a  variable  dependent  on 
the  excitation. 


Sec.  1  DICTIONARY 

CHARGE,  ELECTRIC.  The  quantity  of  electricity  that  exists 
on  the  surface  of  an  insulated  electrified  conductor. 

CHOKE  COIL.  A  reactance  used  in  alternating  current  circuits 
for  the  adjustment  of  voltage  and  power  factor;  and  also  to  impede 
high  frequency  oscillations  such  as  lightning  discharges  in  both 
direct  current  and  alternating  current  circuits. 

CIRCUIT  BREAKER.  Any  device  for  opening  or  breaking  a 
circuit. 

CIRCUIT,  ELECTRIC.  The  path  in  which  electricity  circulates 
or  passes  from  a  given  point,  around  or  through  a  conducting  path, 
back  again  to  its  starting  point. 

All  simple  circuits  consist  of  the  following  parts,  viz : 

(1)  Of  an  electric  source  which  may  be  a  voltaic  battery,  a  thermo- 
pile, a  dynamo-electric  machine,  or  any  other  means  for  pro- 
ducing electricity. 

(2)  Of  leads  or  conductors  for  carrying  the  electricity  out  from 
the  source,  through  whatever  apparatus  is  placed  in  the  line, 
and  back  again  to  the  source. 

(3)  Various  electro-receptive  devices,  such  as  electro-magnets, 
electrolytic  baths,,  electric  motors,  electric  heaters,  etc.,  through 
which  passes  the  current  by  which  they  are  actuated  or  operated. 

CIRCUIT  MULTIPLE.  A  circuit  in  which  a  number  of  separate 
sources  or  separate  electro-receptive  devices  or  both,  each  have  one 
of  their  poles  connected  to  a  single  lead  or  conductor  and  their 
other  poles  connected  to  another  single  lead  or  conductor. 

CIRCUIT,  OPEN.  A  broken  circuit.  A  circuit,  the  conducting 
continuity  of  which  is  broken. 

CIRCUIT,  PARALLEL.  A  name  sometimes  applied  to  circuits 
connected  in  multiple. 

CIRCUIT,  SERIES.  A  circuit  in  which  the  separate  sources  or 
the  separate  electro-receptive  devices,  or  both,  are  so  placed  that 
the  current  produced  in  each,  or  passing  through  each,  passes  suc- 
cessively through  the  entire  circuit  from  the  first  to  the  last. 

CIRCULAR  MIL.  A  unit  of  area  employed  in  measuring  the 
cross-section  of  wires,  equal,  approximately,  to  0.7854  square  mils. 
The  area  of  a  circle  one  mil  in  diameter. 

CLOCKWISE  MOTION.  A  rotary  motion  whose  direction  is 
the  same  as  that  of  the  hands  of  a  clock,  looking  at  the  lace. 

COEFFICIENT  OF  EXPANSIpN.  The  coefficient  of  linear 
expansion  of  a  solid  is  the  increase  in  length  of  unit  length  when  the 
temperature  is  raised  from  32  to  33  degrees  Fah.  or  from  0  to  1 
degree  Cent. 

The  coefficient  of  cubical  expansion  is  the  increase  in  volume  of  a 

[10] 


DICTIONARY  Sec.  1 

body  when  its  temperature  is  raised  from  32  to  33  degrees  Fah.  or 
from  0  to  1  degree  Cent.,  divided  by  its  original  volume. 

COEFFICIENT  OF  HYSTERESIS.  The  work  expended  hys- 
teretically  in  a  cubic-centimetre  of  iron,  or  other  magnetic  substance, 
in  a  single  cycle,  at  unit  magnetic  flux  density.  The  coefficient 
which  multiplied  by  the  volume  of  iron,  the  frequency  of  alternation, 
and  the  1 .6th  power  of  the  maximum  flux  density  gives  the  hysteretic 
power  loss. 

COEFFICIENT  OF  INDUCTANCE.  A  constant  quantity  such 
that,  when  multiplied  by  the  cunent  strength  passing  through  any 
coil  or  circuit,  will  numerically  represent  the  flux  linkage  with  that 
coil  or  circuit  due  to  that  current.  A  term  sometimes  used  for 
coefficient  of  self-induction.  The  ratio  of  the  counter  e.m.f.  of 
self-induction  in  a  coil  or  circuit  to  the  time-rate-of-change  of  the 
inducing  current. 

COEFFICIENT  OF  MUTUAL  INDUCTANCE.  The  ratio  of  the 
electromotive  force  induced  in  a  circuit  to  the  rate-of-change  of  the 
inducing  current  in  a  magnetically  associated  circuit.  The  ratio 
of  the  total  flux-linkage  with  a  circuit  proceeding  from  an  associated 
inducing  circuit,  to  the  strength  of  current  flowing  in  the  latter. 

COEFFICIENT  OF  SELF-INDUCTANCE.  Self-inductance. 
The  ratio  in  any  circuit  of  the  flux  induced  by  and  linked  with  a 
current,  to  the  strength  of  that  current.  The  ratio  in  any  circuit 
of  the  e.m.f.  of  self-induction  to  the  rate-of-change  of  the  current. 

COME  ALONG.  A  small  portable  vise  capable  of  ready 
attachment  to  an  aerial  line  or  cable,  and  used  to  pull  the  wire  to  its 
proper  tension. 

COMMON  RETURN.  A  return  conductor  common  to  several 
circuits. 

COMPENSATOR.    An  auto-transformer. 

COMPLETE  WAVE.  Two  successive  alternations  or  a  double 
alternation  of  a  periodically-alternating  quantity.  A  cycle. 

COMPONENTS  OF  IMPEDANCE.  The  energy  component  or 
effective  resistance  and  the  wattless  component  or  effective  react- 
ance. 

COMPOSITE  WIRE.  A  wire  provided  with  a  steel  core  and  an 
external  copper  sheath,  possessing  sufficient  tensile  strength  to 
enable  it  to  be  used  in  long  spans  without  excessive  sagging.  A 
bimetallic  wire. 

COMPOUND.  An  asphaltic  composition  employed  in  the  sheath- 
ing of  submarine  cables.  A  term  often  applied  to  insulating  ma- 
terials. 

CONCENTRIC  CABLE.  A  cable  provided  with  both  a  leading 
and  return  conductor  insulated  from  each  other,  and  forming  re- 

[11] 


Sec.  1  DICTIONARY 

spectively  the  central  core  or  conductor,  and  the  enclosing  tubular 
conductor.    A  cable  having  concentric  conductors. 

CONDENSANCE.    Capacity  reactance. 

CONDENSER.  A  device  composed  of  two  or  more  conducting 
bodies  separated  by  a  dielectric. 

CONDENSER  CAPACITY.  The  capacity  of  a  condenser.  (See 
Capacity.) 

CONDUCTANCE.  A  word  sometimes  used  in  place  of  conduct- 
ing power.  The  reciprocal  of  resistance.  In  a  continuous-current 
circuit  the  ratio  of  the  current  strength  to  the  e.m.f. ;  in  an  alter- 
nating current  circuit  the  quantity  by  which  the  e.  m.  f .  is  multiplied 
to  give  the  component  of  the  current  in  phase  with  the  e.  m.  f . 

CONDUCTIVITY,  ELECTRIC.  The  reciprocal  of  electric 
resistivity.  The  conductance  of  a  substance  referred  to  unit  dimen- 
sions. 

CONDUCTOR.  Any  substance  which  will  permit  the  so-called 
passage  of  an  electric  current.  A  substance  which  possesses  the 
ability  of  determining  the  direction  in  which  electric  energy  shall 
pass  through  the  ether  in  the  dielectric  surrounding  it. 

CONNECTING  SLEEVE.  A  metallic  sleeve  employed  as  a  con- 
nector for  readily  joining  the  ends  of  two  or  more  wires. 

CONNECTION,  MULTIPLE.  Such  a  connection  of  a  number 
of  separate  electric  sources,  or  electro-receptive  devices,  or  circuits, 
that  all  the  positive  terminals  are  connected  to  one  main  or  positive 
conductor,  and  all  the  negative  terminals  are  connected  to  one  main 
or  negative  conductor. 

CONNECTIpN,  SERIES.  The  connection  of  a  number  of 
separate  electric  sources,  or  electro-receptive  devices,  or  circuits, 
so  that  the  current  passes  successively  from  the  first  to  the  last  in 
the  circuit . 

CONSTANT.  A  quantity  used  in  a  formula,  the  value  of  which 
remains  the  same,  regardless  of  the  value  of  the  other  quantities 
used  in  the  formula. 

CONSTANT  CURRENT.  A  current  maintained  at  a  constant 
effective  value  in  a  circuit  is  known  as  a  constant  current.  This 
maj  be  either  alternating  or  direct  current. 

CONSTANT-CURRENT  TRANSFORMER.  A  transformer  which 
is  intended  to  raise  or  reduce  a  current  strength  in  a  given  constant 
ratio.  A  transformer  designed  to  maintain  a  constant  strength  of 
current  in  its  secondary  circuit,  despite  changes  of  load. 

CONSTANT-POTENTIAL  CIRCUIT.  A  circuit  whose  potential 
is  maintained  approximately  constant.  A  multiple-arc  or  parallel 
connected  circuit. 

[  12] 


DICTIONARY  Sec.  1 

CONTINUOUS  CURRENT.  An  electric  current  which  flows 
in  one  and  the  same  direction.  A  steady  or  non-pulsating  direct 
current. 

CONVECTION  CURRENTS.  Currents  produced  by  the  bodily 
carrying  forward  of  static  charges  in  convection  streams. 

CONVECTIVE  DISCHARGE.  The  discharge  which  occurs  from 
the  points  of  a  highly  charged  conductor,  through  the  electrostatic 
repulsion  of  similarly  charged  air  particles,  which  thus  carry  off 
minute  charges. 

CO-PERIODIC.     Possessing  the  same  periodicity. 

CO-PHASE.  Coincidence  in  phase  of  co-periodic  motions. 
Such  a  phase  relation  between  two  periodic  but  non-co-periodic 
quantities  as  tends  to  increase  the  amplitude  of  the  motion. 

COPPER,  Cu.    Atomic  weight  63.2,  specific  gravity  8.81  to  8.95. 

Fuses  at  about  1930°  F.  Distinguished  from  all  other  metals  by 
its  reddish  color.  Very  ductile  and  malleable  and  its  tenacity  is 
next  to  iron.  Tensile  strength  20,000  to  30,000  Ibs.  per  square  inch. 
Heat  conductivity  73.6%  of  that  of  silver  and  superior  to  that  of 
other  metals.  Expands  0.0051  of  its  volume  bv  heating  from  32° 
to  212°  F. 

COPPER  LOSS.  The  total  loss  of  energy  produced  by  the  pass- 
age of  a  current  through  the  copper  wire  of  a  dynamo,  motor,  or 
conducting  system  generally.  The  loss  of  energy  due  to  the  re- 
sistance of  the  conductor  to  the  passage  of  the  current.  This  loss 
is  equal  to  the  resistance  of  the  conductor  times  the  square  of  the 
effective  current  flowing  in  the  conductor. 

CORE,  LAMINATION  OF.  Structural  subdivisions  of  the  cores 
of  magnets,  transformers,  or  similar  apparatus,  in  order  to  prevent 
heating  and  subsequent  loss  of  energy  from  the  production  of  local 
eddy  or  Foucault  currents. 

These  laminations  are  obtained  by  forming  the  cores  of  sheets, 
rods,  plates,  or  wires  of  iron  insulated  from  one  another. 

CORE  LOSSES.  The  hysteresis  and  the  Foucault  or  eddy- 
current  losses  of  the  core  of  a  dynamo,  motor  or  transformer. 

CORONA.  The  name  given  to  a  brush  discharge  surrounding 
aerial  conductors  which  carry  high  potential.  The  discharge  is  red 
violet  in  color,  gives  a  hissing  sound  and  is  probably  intermittent  in 
character. 

COSINE.  One  of  the  trigonometrical  functions.  The  ratio  of  the 
base  to  the  hypothenuse  of  a  right-angled  triangle  in  which  the  hypo- 
thenuse  is  the  radius  vector,  and  the  angle  between  the  base  and 
hypothenuse  the  angle  whose  cosine  is  considered. 

[  13] 


Sec.  1  DICTIONARY 

COTANGENT.  The  ratio  of  the  adjacent  side  to  the  opposite 
side  of  an  angle  of  a  right  triangle.  Cotangent  6  =  tangent  Q 

COULOMB.  The  practical  unit  of  electric  quantity.  Such  a 
quantity  of  electricity  as  would  pass  in  one  second  through  a  circuit 
conveying  one  ampere. 

The  quantity  of  electricity  contained  in  a  condenser  of  one  farad 
capacity,  when  subjected  to  the  e.m.f.  of  one  volt. 

The  value  of  the  coulomb  as  adopted  by  the  International  Elec- 
trical Congress  of  1893,  at  Chicago.  The  quantity  of  electricity 
equal  to  that  transferred  through  a  circuit  by  a  current  of  one 
International  ampere  in  one  second. 

The  quantity  of  electricity  which  if  concentrated  at  a  point  and 
placed  at  one  centimeter  from  an  exactly  similar  quantity  will  repel 
the  latter  with  a  force  of  one  dyne. 

COUNTER-ELECTROMOTIVE  FORCE.  An  opposite  or  re- 
verse electromotive  force  which  tends  to  set  up  a  current  in  the 
opposite  direction  to  that  actually  produced  by  a  source. 

COUNTER-ELECTROMOTIVE  FORCE  OF  INDUCTION.     The 

counter-electromotive  force  of  self  or  mutual  induction. 

COUPLE.  In  mechanics,  two  equal  and  parallel,  but  oppositely 
directed  forces,  not  acting  in  the  same  line,  and  tending  to  produce 
rotation. 

CROSS  ARM.  A  horizontal  beam  attached  to  a  pole  for  the 
support  of  the  insulators  of  electric  light,  or  other  electric  wires. 

CROSS,  ELECTRIC.  A  connection,  generally  metallic,  acci- 
dentally established  between  two  conducting  lines.  A  defect  in  an 
electric  circuit,  caused  by  two  wires  coming  into  contact  by  crossing 
each  other. 

CURRENT  DISTRIBUTION.  The  density  of  electric  currents  in 
the  various  parts  of  a  conducting  mass  or  net  work. 

CURRENT  DETERMINATION  FROM  WATTAGE.  The  rated 
current  may  be  determined  as  follows:  If  W  =  rating  in  watts,  or 
apparent  watts,  if  the  power-factor  be  other  than  100  per  cent,  and 
E  =  full-load  terminal  voltage,  the  rated  current  per  terminal  is: 

W 
I  =  -=7-  in  continuous  current,  or  single-phase  apparatus 

El 

•«T 

in  three-phase  apparatus 


V3-E 

W 

I  =  2^  in  two-phase  four  wire  apparatus. 

CURRENT,  ELECTRIC.    The  quantity  of  electricity  per  second 
which  passes  through  any  conductor  or  circuit,  when  the  flow  is 

[14] 


DICTIONARY  Sec.  1 

uniform.  The  rate  at  which  a  quantity  of  electricity  flows  or  passes 
through  a  circuit.  ^  The  ratio,  expressed  in  terms  of  electric  quantity 
per  second,  existing  between  the  electromotive  force  causing  a 
current  and  the  resistance  which  opposes  it. 

The  unit  of  current,  or  the  ampere,  is  equal  to  one  coulomb  per 
second.  (See  Ampere,  and  Coulomb.) 

The  word  current  must  not  be  confounded  with  the  mere  act  of 
flowing;  electric  current  signifies  rate  of  flow,  and  always  supposes 
an  electromotive  force  to  produce  the  current,  and  a  resistance  to 
oppose  it. 

The  electric  current  is  assumed  to  flow  out  from  the  positive 
terminal  of  a  source,  through  the  circuit  and  back  into  the  source 
at  the  negative  terminal  It  is  assumed  to  flow  into  the  positive 
terminal  of  an  electro  receptive  device  such  as  a  lamp,  motor,  or 
storage  battery,  and  out  of  its  negative  terminal;  or,  in  other  words, 
the  positive  pole  of  the  source  is  always  connected  to  the  positive 
terminal  of  the  electro-receptive  device. 

The  current  that  flows  or  passes  in  any  circuit  is,  in  the  case  of  a 
constant  current,  equal  to  the  electromotive  force,  or  difference  of 
potential,  divided  by  the  resistance,  as: 

D.  C,  A.  C. 

T       B  T        E 

=  R  I  =  Z 

The  flow  of  an  electric  current  may  vary  in  any  manner  whatsoever. 
A  current  which  continues  flowing  in  the  same  direction  no  matter 
how  its  strength  may  vary,  is  called  a  direct  current.  If  the  strength 
of  such  a  current  is  constant,  it  is  called  a  continuous  current.  A 
regular  varying  continuous  current  is  called  a  pulsatory  current. 
A  current  which  alternately  flows  in  opposite  directions,  no  matter 
how  its  strength  may  vary,  is  called  an  alternating  current.  This 
may  be  periodic  or  non-periodic. 

CURRENT,  FOUCAULT.  A  name  sometimes  applied  to  eddy 
currents,  especially  in  armature  cores. 

CURRENT,  POLYPHASE,  is  the  general  term  applied  to  any 
system  of  more  than  a  single  phase. 

CURRENT  RUSH.  The  initial  flow  of  electricity  that  occurs 
when  a  transformer,  transmission  line  or  other  electrical  apparatus 
is  switched  on  or  connected  to  an  electric  circuit. 

CURRENT,  SIMPLE  PERIODIC.  A  current,  the  flow  of  which 
is  variable  both  in  strength  and  duration,  but  recurring  at  definite 
intervals.  A  flow  of  current  passing  any  section  of  a  conductor  that 
may  be  represented  by  a  simple  harmonic  curve. 

CURRENT  STRENGTH.  In  a  direct-current  circuit  the  quo- 
tient of  the  total  electromotive  force  divided  by  the  total  resistance. 
The  time-rate-of-flow  in  a  circuit  expressed  in  amperes,  or  coulombs 

[  15  ] 


Sec.  1  DICTIONARY 

per  second.     In  an  alternating  current  the  quotient  of  the  total 
electromotive  force  divided  by  the  impedance. 

CUT-OUT.  A  device  for  removing  an  electro-receptive  device 
or  loop  from  the  circuit.  A  safety  fuse. 

CUT-OUT-BLOCK.  A  block  containing  a  fuse  wire  or  safety 
catch. 

CUT-OUT-SWITCH.  A  short-circuiting  switch  by  means  of 
which  an  arc-light  or  series  loop  is  cut  out  from  its  feeding  circuit. 

CYCLEi  One  complete  set  of  positive  and  negative  values  of  3n 
alternating  current. 

D. 

D.  C.     An  abbreviation  for  direct  current. 

D.  P.  SWITCH.    An  abbreviation  for  double-pole  switch. 

DEAD  MAN.  A  support  for  raising  a  pole  and  supporting  it  in 
place  while  securing  it  in  the  ground. 

DELTA-CONNECTION.  The  connection  of  circuits  employed 
in  a  delta  three  phase  system. 

DELTA  THREE  PHASE  SYSTEM.  A  three  phase  system  in 
which  the  terminal  connections  resemble  the  Greek  letter  delta,  or 
a  triangle. 

DEMAND.  Demand  is  a  load  specified,  contracted  for  or  used, 
expressed  in  terms  of  power  as  kilowatts  or  horse-power. 

DEMAND  FACTOR.  Unless  otherwise  specified,  demand  factor 
is  the  maximum  connected  kilowatts  of  capacity  divided  into  the 
actual  kilowatts  of  demand,  and  expressed  in  terms  of  percent. 

DENSITY.     Mass  of  unit  volume,  compactness. 

DENSITY  OF  CURRENT.  The  quantity  of  current  that  passes 
per-unit-of-area  of  cross-section  in  any  part  of  a  circuit. 

DENSITY  OF  FIELD.  The  quantity  of  magnetic  flux  that  passes 
through  any  field  per-unit-of-area  of  cross-section. 

DIELECTRIC.  Any  substance  which  permits  electrostatic  in- 
duction to  take  place  through  its  mass. 

The  substance  which  separates  the  opposite  coatings  of  a  con- 
denser is  called  the  dielectric.  All  dielectrics  are  non-conductors. 

All  non-conductors  or  insulators  are  dielectrics,  but  their  dielectric 
power  is  not  exactly  proportional  to  their  non-conducting  power. 

Substances  differ  greatly  in  the  degree  or  extent  to  which  they 
permit  induction  to  take  place  through  or  across  them. 

A  dielectric  may  be  regarded  as  pervious  to  rapidly  reversed 
periodic  currents,  but  opaque  to  continuous  currents.  There  is, 
however,  some  conduction  of  continuous  currents. 

[16] 


DICTIONARY  Sec.  1 

DIELECTRIC  CAPACITY.  A  term  employed  in  the  same  sense 
as  specific  inductive  capacity. 

DIELECTRIC  HYSTERESIS.    A  variety  of  molecular  friction, 

analogous  to  magnetic  hysteresis,  produced  in  a  dielectric  under 
charges  of  electrostatic  stress.  That  property  of  a  dielectric  by 
virtue  of  which  energy  is  consumed  in  reversals  of  electrification. 

DIELECTRIC  RESISTANCE.  The  resistance  which  a  dielectric 
offers  to  strains  produced  by  electrification.  The  resistance  of  a 
dielectric  to  displacement  currents. 

DIELECTRIC  STRAIN.  The  strained  condition  of  the  glass  or 
other  dielectric  of  a  condenser  produced  by  the  charging  of  the  con- 
denser. The  deformation  of  a  dielectric  under  the  influence  of  an 
electro-magnetic  stress. 

DIPPING.  An  electro-metallurgical  process  whereby  a  thin 
coating  or  deposit  of  metal  is  obtained  on  the  surface  of  another 
metal  by  dipping  it  in  a  solution  of  a  readily  decomposable  metallic 
salt.  Cleansing  surfaces  for  electric-plating  by  immersing  them  in 
various  acid  liquors. 

DISCHARGE.  The  equalization  of  the  difference  of  potential 
between  the  terminals  of  a  condenser  or  source,  on  then*  connection 
by  a  conductor.  The  removal  of  a  charge  from  a  conductor  by 
connecting  the  conductor  to  the  earth  or  to  another  conductor.  The 
removal  of  a  charge  from  an  insulated  conductor  by  means  of  a 
stream  of  electrified  air  particles. 

DISRUPTIVE  DISCHARGE.  A  sudden  and  more  or  less  com- 
plete discharge  that  takes  place  across  an  intervening  non-conductor 
or  dielectric. 

DISRUPTIVE  STRENGTH  OF  DIELECTRIC.    The  strain  a 

dielectric  is  capable  of  bearing  without  suffering  disruption,  or  with- 
out permitting  a  disruptive  discharge  to  pass  through  it. 

DISSIPATION  OF  ENERGY.  The  expenditure  or  loss  of  avail- 
able energy. 

DISTRIBUTED  CAPACITY.  The  capacity  of  a  circuit  con- 
sidered as  distributed  over  its  entire  length,  so  that  the  circuit  may 
be  considered  as  shunted  by  an  infinite  number  of  infinitely  small 
condensers,  placed  infinitely  near  together,  as  distinguished  from 
localized  capacity,  in  which  the  capacity  is  distributed  in  definite 
aggregations. 

DISTRIBUTED  INDUCTANCE.  Inductance  distributed  through 
the  entire  length  of  a  circuit  or  portion  thereof,  as  distinguished  from 
inductance  interposed  in  a  circuit  in  bulk  at  some  one  or  more 
points. 

DISTRIBUTING  CENTER.     (See  Center  of  Distribution.) 

[17] 


Sec.  1  DICTIONARY 

DISTRIBUTING  MAINS.  The  mains  employed  in  a  feeder 
system  of  parallel  distribution. 

DIVERSITY  FACTOR.  A  diversity  factor  is  used  to  express  the 
relation  between  the  simultaneous  demand  of  all  individual  con- 
sumers and  the  sum  of  the  maximum  demands  made  by  these  con- 
sumers; the  sum  of  the  maximum  demands  of  the  consumers  for  one 
year,  no  matter  at  what  time  they  occurred,  divided  into  the  simul- 
taneous greatest  demand  of  these  consumers  for  a  like  period,  when 
expressed  in  percent  will  give  the  diversity  factor. 

DRAW  VISE.  A  device  employed  in  stringing  overhead  wires. 
A  portable  vise  for  holding  and  drawing  up  an  overhead  wire. 

DROP.  A  word  frequently  used  for  drop  of  potential,  pressure, 
or  electromotive  force.  The  fall  of  potential  which  takes  place  in 
an  active  conductor  by  reason  of  its  resistance,  or  impedance. 

DROP  OF  POTENTIAL.  The  fall  of  potential,  equal  in  any  part 
of  a  circuit  to  the  product  of  the  current  strength  and  the  resistance, 
or  impedance  of  that  part  of  the  circuit. 

DROP  OF  VOLTAGE.  The  drop  or  difference  of  potential  of 
any  part  of  a  circuit. 

DUPLEX  CABLE.  A  cable  containing  two  separate  conductors 
placed  parallel  to  each  other. 

DUPLEX  WIRE.  An  insulated  conductor  containing  two  sepa- 
rately insulated  parallel  wires. 

DYNAMIC  ELECTRICITY.  A  term  sometimes  employed  for 
the  phenomena  of  the  transfer  of  electric  energy,  in  contradistinction 
to  static  electricity. 

DYNE.  The  C.G.S.  unit  of  force.  The  force  which  in  one 
second  can  impart  a  velocity  of  one  centimeter-per-second  to  a 
mass  of  one  gramme. 

E. 

e.  h.  p.    An  abbreviation  for  electrical  horse-power, 
e.  m.  f.    An  abbreviation  for  electromotive  force.  - 

e.  m.  f .  OF  SELF-INDUCTION.  The  e.m.f .  generated  in  a  loop 
oi  wire  during  the  change  of  magnetic  flux  due  to  the  current  flowing 
therein. 

EARTH  CIRCUIT.  A  circuit  in  which  the  ground  or  earth  forms 
part  of  the  conducting  path. 

EARTH  CURRENTS.  Electric  currents  flowing  through  the 
earth,  caused  by  the  difference  of  potential  of  its  different  parts. 

EASEMENT.  A  permit  obtained  from  the  owner  of  a  property 
for  the  erection  of  poles  or  attachments  for  aerial  lines. 

[18] 


DICTIONARY  Sec.  1 

EDDY  CURRENTS.     (See  Foucault  currents.) 

EFFECTIVE  ELECTROMOTIVE  FORCE.  The  difference  be- 
tween the  direct  and  the  counter  e.m.f.  The  square  root  of  the 
mean  square  of  the  instantaneous  values  of  a  varying  electromotive 
force.  The  value  which  is  equivalent  to  a  constant  electromotive 
force. 

EFFECTIVE  REACTANCE.  In  an  alternating-current  circuit, 
the  ratio  of  the  wattless  component  of  an  electromotive  force  to  the 
total  current. 

EFFECTIVE  RESISTANCE.  In  an  alternating-current  circuit, 
the  ratio  between  the  energy  component  of  an  electromotive  force 
and  the  total  current. 

EFFICIENCY.  The  efficiency  of  an  apparatus  is  the  ratio  of  its 
output  to  its  input.  The  output  and  input  may  be  in  terms  of  watt- 
hours,  watts,  volt-amperes,  amperes,  or  any  other  quantity  of  interest, 
thus  respectively  defining  energy  efficiency,  power  efficiency,  ap- 
parent-power efficiency,  current  efficiency,  etc.  Unless  otherwise 
specified,  however,  the  term  efficiency  is  ordinarily  assumed  to  refer 
to  power  efficiency. 

When  the  input  and  output  are  expressed  in  terms  of  the  same 
unit,  the  efficiency  is  a  numerical  ration,  otherwise  it  is  a  physical 
dimensional  quantity. 

ELASTIC  LIMIT.  This  may  be  defined  as  that  point  at  which 
the  deformation  ceases  to  be  proportional  to  the  stresses,  or,  the 
point  at  which  the  rate  of  stretch  or  other  deformations  begin  to 
increase.  It  is  also  defined  as  the  point  at  which  permanent  set 
becomes  visible. 

ELECTRIFICATION.    The  production  of  an  electric  charge. 

ELECTRO-CHEMISTRY.  That  branch  of  electric  science  which 
treats  of  electric  combinations  and  decompositions  effected  by  the 
electric  current.  The  science  which  treats  of  the  relation  between 
the  laws  of  electricity  and  chemistry. 

ELECTRO-MAGNETIC  UNITS.  A  system  of  C.G.S.  units 
employed  in  electro-magnetic  measurements.  Units  based  on  the 
attraction  and  repulsions  capable  of  being  exerted  between  two  unit 
magnetic  poles  at  unit  distance  apart,  or  between  a  unit  magnetic 
pole  and  a  unit  electric  current. 

ELECTRO-METALLURGY.  That  branch  of  electric  science 
which  relates  to  the  electric  reduction  or  treatment  of  metals. 
Electro-metallurgical  processes  effected  by  the  agency  o^  electricity. 
Electro-plating  or  electro-typing. 

ELECTRO-NEGATIVE.  In  such  a  state  as  regards  electricity 
as  to  be  repelled  by  bodies  negatively  electrified,  and  attracted  by 

[19] 


Sec.  1  DICTIONARY 

those  positively  electrified.    The  ions  or  radicals  which  appear  at 
the  anode  or  positive  electrode  of  a  decomposition  cell. 

ELECTRO-NEGATIVE  IONS.  The  negative  ions,  or  groups  of 
atoms  or  radicals,  which  appear  at  the  anode  or  positive  terminal  of 
a  decomposition  cell.  The  anions. 

ELECTRO-PLATING.  The  process  of  covering  any  conducting 
surface  with  a  metal,  by  the  aid  of  an  electric  current. 

ELECTRO-POSITIVE.  In  such  a  state,  as  regards  an  electric 
charge,  as  to  be  attracted  by  a  body  negatively  electrified,  and 
repelled  by  a  body  positively  electrified.  The  ions  or  radicals  which 
appear  at  the  cathode  or  negative  electrode  of  a  decomposition  cell. 

ELECTRO-POSITIVE  IONS.  The  cations  or  groups  of  atoms 
or  radicals  which  appear  at  the  cathode  of  a  decomposition  cell. 

ELECTROLYSIS.  Chemical  decomposition  effected  by  means 
of  an  electric  current.  The  decomposition  of  the  molecule  of  an 
electrolyte  into  its  ions  or  radicals.  Electrolytic  decomposition. 

ELECTROLYTE.  Any  compound  liquid  which  is  separable  into 
its  constituent  ions  or  radicals  by  the  passage  of  electricity  through 
it. 

ELECTROLYTIC  CELL.  A  cell  or  vessel  containing  an  electro- 
lyte in  which  electrolysis  is  carried  on.  A  plating  cell  or  vat. 

ELECTROSTATIC  CAPACITY.     (See  Capacity  Electrostatic.) 

ELECTROSTATIC  DISCHARGE.  A  term  sometimes  employed 
for  a  disruptive  discharge. 

ELECTROSTATIC  FIELD.  The  region  of  stress  existing  about 
an  electrified  body  due  to  its  electric  potential. 

ELECTROSTATIC  FORCE.  The  force  of  attraction  or  repulsion 
exerted  between  two  electrified  bodies  due  to  their  potentials. 

ELECTROSTATIC  INDUCTION.  The  induction  of  an  electric 
charge  produced  in  a  conductor  brought  into  an  electrostatic  field. 

ELECTROSTATIC  LINES  OF  FORCE.  Lines  of  force  produced 
in  the  neighborhood  of  a  charged  body,  by  the  presence  of  the 
charge.  Lines  extending  in  the  direction  in  which  the  force  of 
electrostatic  attraction  or  repulsion  acts. 

ELECTROSTATIC  POTENTIAL.  The  power  of  doing  electric 
work  possessed  by  a  unit  quantity  of  electricity  residing  on  the  surface 
of  an  insulated  body.  That  property  in  space  by  virtue  of  which 
work  is  done  when  an  electric  charge  is  moved  therein. 

ELECTROSTATIC  UNITS.  Units  based  on  the  attractions  or 
repulsions  of  two  unit  charges  of  electricity  at  unit  distance  apart. 

ENERGY.     The  power  of  doing  work. 

[20] 


DICTIONARY  Sec.  1 

ENERGY  COMPONENT  OF  E.M.F.  In  an  alternating  current 
circuit  the  component  of  e.m.f.  which  is  in  phase  with  the  current. 
In  an  alternating  current  circuit,  the  product  of  the  current  and  the 
effective  resistance. 

ENERGY  COMPONENT  OF  CURRENT.  In  an  alternating 
current  circuit  the  component  of  current  which  is  in  phase  with  the 
impressed  e.m.f.  In  an  alternating  current,  the  product  of  the 
e.m.f.  and  the  effective  conductance. 

ENERGY,  ELECTRIC.  The  power  which  electricity  possesses 
of  doing  work. 

EQUALIZER  FEEDER.  A  feeder  whose  principal  purpose  is  to 
equalize  the  pressure  between  the  ends  of  two  or  more  other  feeders, 
as  distinguished  from  supplying  current  to  feeding  points. 

EQUIPOTENTIAL.    Of,  or  pertaining  to  an  equality  of  potential. 

EQUIVALENT  RESISTANCE.  A  single  resistance  which  may 
replace  a  number  of  resistances  in  a  circuit  without  altering  the 
current  traversing  it.  Such  a  resistance  in  a  simple-harmonic-current 
circuit  as  would  permit  energy  to  be  absorbed,  with  the  same  ef- 
fective current  strength,  at  the  same  rate  as  an  actual  resistance  in 
a  complex-harmonic-current  circuit. 

ERG.  The  C.G.S.  unit  of  work,  or  the  work  done  when  unit 
C.  G.  S.  force  is  overcome  through  unit  C.  G.  S.  distance.  The  work 
accomplished  when  a  body  is  moved  through  a  distance  of  one 
centimeter  with  the  force  of  one  dyne.  A  dyne-centimeter. 

F. 

FAHRENHEIT  THERMOMETRIC  SCALE.  The  thermometric 
scale  in  which  the  length  of  the  thermometer  tube,  between  the 
melting  point  of  ice  and  the  boiling  point  of  water,  is  divided  into 
180  equal  parts  or  degrees. 

FARAD.  The  practical  unit  of  electric  capacity.  Such  a  capacity 
of  a  conductor  or  condenser  that  one  coulomb  of  electricity  is  re- 
quired to  produce  therein  a  difference  of  potential  of  one  volt. 

FATIGUE  OF  IRON  OR  STEEL,  MAGNETIC.  The  change 
of  magnetic  hysteresis  loss  with  time.  Ageing  of  magnetic  material. 

FEED.  To  supply  with  an  electric  current.  To  move  or  regulate 
one  or  both  of  the  carbon  electrodes  in  an  arc-lamp. 

FEEDER.  An  electric  circuit,  used  to  supply  power  to  a  station 
or  service,  as  distinguished  from  circuits  confined  to  a  single  station. 

FEEDER  DISTRIBUTION.  A  feeder-and-main  system  of  dis- 
tribution. 

[21] 


Sec.  1 


DICTIONARY 


FEEDING  POINT.  A  point  of  connection  between  a  feeder  and 
the  mains.  A  feeding  center. 

FIELD,  ELECTROSTATIC.     (See  Electrostatic  Field.) 

FIELD,  MAGNETIC.  The  region  of  stress  existing  around  the 
poles  of  a  magnet  or  a  magnetized  body,  with  reference  to  its  effect 
upon  a  unit  magnetic  charge.  Also  the  field  around  a  conductor 
due  to  a  current  flowing  in  it. 

FOOT-POUND.  A  unit  of  work.  The  amount  of  work  required 
to  raise  one  pound  vertically  through  a  distance  of  one  foot. 

FOOT-POUND-PER-SECOND.  A  rate  of  doing  work  equal  to 
the  expenditure  of  one  foot-pound  of  energy  per  second. 

FOUCAULT  OR  EDDY  CURRENTS.  It  was  observed  a  num- 
ber of  years  before  Faraday's  discovery  of  induced  currents,  that,  a 
vibrating  magnetic  needle  quickly  came  to  rest  when  near  or  over 
a  copper  plate.  Arago  had  in  1824  also  shown  that  a  magnetic  needle 
suspended  over  a  rotating  copper  disk  rotates  with  the  disk.  Both 


FIG.   1. — Foucault  Currents  Generated 
in  Disk  by  Arago's  Rotation. 


FIG.  2. — Another  Form  of  Arago's 
Experiment. 


the  damping  of  the  needle  and  Arago's  disk  experiment  were  ex- 
plained by  Faraday  as  phenomena  of  electro-magnetic  induction. 
The  relative  motion  of  the  magnet  and  the  disk  induces  an  e.m.f. 
in  the  metal  disk.  The  current  thus  generated  circulates  in  the 
disk,  producing  a  magnetic  action,  which  by  Lenz's  law  tends  to 
hold  the  magnet  at  rest  relative  to  the  disk  or  plate. 

Electric  currents,  thus  induced  and  circulating  in  a  metallic  mass, 
are  called  eddy  currents  or  Foucault  currents.  The  energy  of  such 
currents  is  dissipated  in  heat.  The  iron  cores  of  armatures  of 
dynamo  machines  and  transformers  are  always  laminated  so  as  to 
offer  resistance  to  the  formation  of  such  currents,  and  thus  to  stop 
the  heat  losses  (Figs.  1  and  2). 

FREQUENCY.     The  number  of  cycles  or  periods  per  second. 

[22] 


DICTIONARY  Sec.  1 

FUNDAMENTAL  FREQUENCY.  The  nominal  or  lowest 
frequency  of  a  complex  harmonic  electromotive  force,  flux  or  current. 

FUSE  BLOCK.     A  block  containing  a  safety  fuse,  or  fuses. 

FUSE  BOX.  A  box  containing  a  safety  fuse.  A  box  containing 
fuse  wires. 

FUSE,  ELECTRIC.  A  conductor  designed  to  melt  or  fuse  at  a 
certain  value  of  current  and  time  and  by  so  doing  to  rupture  the 
circuit. 

FUSE  LINKS.  Strips  or  plates  of  fusible  metal  in  the  form  of 
links  employed  for  safety  fuses. 

FUSING  CURRENT.  A  term  sometimes  applied  to  the  current 
which  causes  a  fuse  to  melt. 

G. 

g.  An  abbreviation  or  symbol  for  the  gravitation  constant,  or 
the  force  with  which  the  earth  acts  upon  unit  mass  at  any  locality. 
An  abbreviation  proposed  for  gramme,  the  unit  of  mass  in  physical 
investigations. 

GAINS.  The  spaces  cut  in  poles  for  the  support  and  placing  of 
the  cross  arms. 

GALVANIZING.  Covering  iron  with  an  adherent  coating  of 
zinc  by  dipping  it  in  a  bath  of  molten  metal. 

GAUSS.  The  name  proposed  in  1894  by  the  American  Institute 
of  Electrical  Engineers  for  the  C.G.S.  unit  of  magnetic  flux  density. 
A  unit  of  intensity  of  magnetic  flux,  equal  to  one  C.G.S.  unit  of 
magnetic  flux  per-square-centimeter  of  area  of  normal  cross-section. 
A  name  proposed  for  the  C.G.S.  unit  of  magnetic  potential  or  mag- 
netomotive force  by  the  British  Association  in  1895. 

GILBERT.  A  name  proposed  for  the  C.G.S.  unit  of  magneto- 
motive force.  A  unit  of  magnetomotive  force  equal  to  that  produced 

bv - —  of  one  ampere-turn.    That  value  of  magnetic  force  which 

1.25oo 

will  establish  one  line  or  one  maxwell  per  centimeter  cube  of  air. 

GLOBE  STRAIN-INSULATORS.  Insulators  provided  for  the 
support  of  the  strain  wires  in  an  overhead  system. 

GRADIENT,  ELECTRIC.  The  rapidity  of  increase  or  decrease 
of  the  strength  of  an  electromotive  force.  The  vector  space-rate 
of  descent  of  electric  potential  at  any  point. 

GRAPHITE.  Graphite  is  used  for  rendering  surfaces  to  be  elec- 
tro-plated, electrically  conducting,  and  also  for  the  brushes  of  dyna- 
mos and  motors.  For  the  latter  purpose  it  possesses  the  additional 
advantage  of  decreasing  the  friction  by  means  of  its  marked  lubri- 
cating properties. 

[  23  ] 


Sec.  1 


DICTIONARY 


GROUND.  A  general  term  for  the  earth  when  employed  as  a 
return  conductor.  A  term  for  the  connection  of  a  conductor  to  the 
earth. 

GROUND  CIRCUIT.  A  circuit  in  which  the  ground  forms  part 
of  the  path  through  which  the  current  passes. 

GROUND,  EFFECT  OF.  On  the  neutral  point  of  three-phase, 
three-wire  systems.  Consider  a  general  case.  A  lightning  stroke 
disables  some  apparatus  so  that  inductive  reactance  is  introduced 
in  the  accidental  ground.  Before  the  accident  there  was  a 
perfectly  balanced  system,  where  the  neutral,  or  ground  potential, 
is  symmetrical  in  reference  to  the  line  conductors  and  governed 

A 
I 


13 

FIG.  3. 


FIG.  4. 


FIG.  5. 


entirely  by  the  ground  capacities  represented  in  Fig.  3,  as  three  con- 
densers. If,  now,  one  line  is  grounded  through  an  impedance,  the 
neutral  will  be  displaced  along  line  AB. 

The  conditions  are  then  : 

First.  Ground  made  by  infinite  reactance.  (No  Ground.)  We 
have  then 


X  = 


—  -  and  e2  =  —  when 


is  the  voltage  from  one  wire 


to  the  neutral  of  a  balance  system  and  e2  is  the  voltage  from  the 
neutral  of  the  balanced  system  to  a  point  midway  between  the  other 
two  wires  and  X  is  the  condensive  reactance;  that  is,  in  Fig.  4  the 
neutral  lies  at  O,  and  the  ground  is  symmetrical  in  reference  to  the 
three  lines. 

Second,  when  e2  =  0,  and  ei=e  (shown  in  Fig.  5). 

In  this  case  the  neutral  lies  midway  between  the  other  two  con- 
ductors and  its  potential  difference  -to  ground  is  .87e. 

Third,  when  ei  and  e2  both  become  infinite,  under  such  condition, 
the  system  would  be  subjected  to  infinite  potential.  The  third  con- 
dition arises  if  one  line  is  grounded  by  a  reactance  of  |  of  the  con- 
densive reactance,  the  system  then  being  subjected  to  very  great 
stresses,  even  at  normal  frequency. 

GROUND-RETURN.  A  general  term  used  to  indicate  the  use 
of  the  ground  or  earth  for  part  of  an  electric  circuit.  The  earth  or 
ground  which  forms  part  of  the  return  path  of  an  electric  circuit. 

[24] 


DICTIONARY 


£\ 


A 


"\ 


560   V/ 


<r     \^/    iwvy       \yj 

^  /rx  /\  / 

y  ~  o 

/rx 


Sec.  1 

GUTTA-PERCHA.  A 
resinous  gum  obtained 
from  a  tropical  tree,  and 
valuable  electrically  for 
its  high  insulating  powers. 

GUY.  A  rod,  chain, 
rope,  or  wire  employed 
for  supporting  or  stiffen- 
ing any  structure  such  as 
a  pole. 

GUY  WIRE.  A  wire 
employed  as  a  guy. 

H. 

H.  An  abbreviation  for 
the  henry  or  practical  unit 
of  self  induction. 


v 


FIG.  6.  —  Relations  of  the  Fundamental  e.m.f. 
and  Triple  Harmonics  in  a  Delta  Connected 
Circuit. 


H.  A  symbol  for  field 
intensity. 

M.  An  abbreviation 
for  the  magnetizing  force 
that  exists  at  any  point, 
or.  generally  for  the 


w 


.e  m- 
magnetic 


tensity     of 
force. 


H.B.  CURVES.  Curves 
indicating  the  relations 
between  magnetizing  force 
and  magnetic  flux  density 
in  a  magnetic  substance. 
A  term  sometimes  em- 
ployed for  magnetization 
curves. 

H.P.  An  abbreviation 
for  horse-power. 

HALL     EFFECT.       A 

transverse     electromotive 


\ 


FIG?.—  Relation  of  the  Fundamental  e.m.f.  and 
Triple  Harmonics  in  a  Star  Connected  Circuit. 
[  25  ] 


Sec.  1 


DICTIONARY 


force  produced  by  a  magnetic  field  in  substances  undergoing  electric 
displacement. 

HARD-DRAWN  COPPER  WIRE.  Copper  wire  that  is  hardened 
by  being  drawn  three  or  four  times  without  annealing.  Copper 
wire  not  annealed  after  leaving  the  die. 

HARMONIC  CURRENTS.  Periodically  alternating  currents 
varying  harmonically.  Currents  which  are  harmonic  functions  of 
time.  Sinusoidal  currents. 

In  modern  alternators  an  endeavor  is  made  to  shape  the  magnetic 
circuit  so  that  the  e.m.f.  is  a  sine  wave,  nevertheless,  a  triple  har- 
monic of  some  magnitude  usually  exists  in  the  e.m.f.  wave  of  single- 


36  0* 


FIG.  8. 


phase  alternators,  and  in  each  of  the  individual  phases  of  a  polyphase 
generator. 

The  e.m.f.  between  two  terminals  of  a  three-phase  generator, 
does,  however,  not  contain  any  triple  harmonic  for  the  following 
reasons: 

Consider  first  in  Fig.  6  a  delta-connected  three-phase  generator, 
in  each  phase  of  which  is  a  prominent  triple  harmonic;  a,  b  and  c 
represent  the  three  e.m.f.'s  as  displaced  120  degrees.  It  is  seen  that 
the  three  triple  harmonics  are  in  phase,  thus  the  machine  is  really 
running  under  short  circuit  as  far  as  the  triple  harmonic  is  concerned. 

[  26] 


DICTIONARY 


Sec.  1 


A  triple  frequency  current  will  be  established,  which  will  consume 
the  e.m.f.  which,  therefore,  will  not  appear  in  the  terminal  e.m.f. 

The  triple  harmonic  current  will,  however,  set  up  an  armature 
reaction  which  will  distort  the  field  magnetism  and  thereby  cause  a 


FIG.  9. 

fifth  and  seventh  harmonic.     With  star  connection  the  terminal 


FIG.  10. 


the  resultant  of  OA  and  OB,  thus  OA  — OB  (the  minus  sign  on  ac- 
count of  the  direction) .  In  a  are  given  the  e.m.f. 's  in  OA,  in  b  are 
given  the  e.m.f  .'s  of  OB ;  and  their  resultant  (with  OB  reversed)  is 

f  27.1 


Sec.  1 


DICTIONARY 


c.  The  triple  harmonic  again  has  disappeared,  but  the  fundamental 
is  larger  than  in  the  individual  phase.  In  the  e.m.f.  against  the 
neutral  or  ground  the  triple  harmonic  exists;  therefore,  the  charging 
current  against  ground  will  be  of  triple  frequency  and  any  multiple 
thereof,  if  permitted  to  exist,  that  is,  if  the  generator  neutral  is 
grounded. 
The  transformers  are  a  source  of  triple  harmonic  e.m.f  .'s  or  cur- 


rents, but  this  can  also  be  eliminated  if  one  side  of  the  transformers 
is  delta  connected,  as  should  always  be  the  case. 

In  general,  it  can  be  said  that  the  triple  harmonics  should  give  no 
difficulties  in  a  three-phase  transmission;  it  need  not  exist. 

[28] 


DICTIONARY 


Sec.  1 


HARMpNICS,  EFFECTS  OF  HIGHER.  To  elucidate  the 
variation  in  the  shape  of  alternating  waves  caused  by  various  har- 
monics, in  Fig.  8,  Fig.  9,  Fig.  10,  and  Fig.  11  are  illustrated  the  wave 
forms  produced  by  the  super-imposition  of  the  double,  triple  and 
the  quintuple  harmonic  upon  the  fundamental  sine  wave. 

In  Fig.  12  is  shown  the  fundamental  sine  wave  and  the  complex 


360° 


360* 


FIG.  12. — Various  Distortions  of  the  Fundamental  Wav  e  by  Triple  Harmonic  in 
Different  Phase  Relation  to  the  Fundamental. 


waves  produced  by  the  superimposition  of  a  triple  harmonic  of  30 
percent  of  the  amplitude  of  the  fundamental,  under  the  relative 
phase  displacements  of  0,  45,  90,  135  and  180  degrees. 

[29] 


Sec.  1 


DICTIONARY 


As  seen,  the  effect  of  the  triple  harmonic  is  in  the  first  figure  to 
flatten  the  zero  values  and  point  the  maximum  values  of  the  wave, 
giving  what  is  called  a  peaked  wave.  With  increasing  phase  dis- 
placement of  the  triple  harmonic,  the  flat  zero  rises  and  gradually 


FIG.  13. — Various  Distortions  of  the  Fundamental  Wave  by  Triple  and 
Quintuple  Harmonics  of  Characteristics  given  Below  : 

1.  15%  3rd,  <f>  =      0  10%  5th,  0  =     0 

2.  22i%  3rd,  0  =  180  5%  5th,  <f>  =  180 

3.  15%  3rd,  <f>  =  180  10%  5th,  <f>  =     0 

4.  15%  3rd,  0  =     0  10%  5th,  <£  =  180 

[30] 


DICTIONARY  Sec.  1 

changes  to  a  second  peak,  giving  ultimately  a  flat-top  or  even  double- 
peaked  wave  with  sharp  zero.  The  intermediate  positions  represent 
what  is  called  a  saw-tooth  wave. 

The  quintuple  harmonic  causes  a  flat-topped  or  even  double- 
peaked  wave  with  flat  zero.  With  increasing  phase  displacement, 
the  wave  becomes  of  the  type  called  saw-tooth  wave  also.  The 
flat  zero  rises  and  becomes  a  third  peak,  while  of  the  two  former 
peaks,  one  rises,  the  other  decreases,  and  the  wave  gradually  changes 
to  a  triple-peaked  wave  with  one  main  peak,  and  a  sharp  zero. 

As  seen,  with  the  triple  harmonic,  flat-top  or  double-peak  coin- 
cides with  sharp  zero,  while  the  quintuple  harmonic  flat-top  or 
double-peak  coincides  with  flat  zero. 

Sharp  peak  coincides  with  flat  zero  in  the  triple,  with  sharp  zero 
in  the  quintuple  harmonic.  With  the  triple  harmonic,  the  saw-tooth 
shape  appearing  in  case  of  a  phase  difference  between  the  funda- 
mental and  harmonic,  is  single,  while  with  the  quintuple  harmonic 
it  is  double. 

Thus  in  general,  from  simple  inspection  of  the  wave  shape,  the 
existence  of  these  first  harmonics  can  be  discovered.  Some  char- 
acteristic shapes  are  shown  in  Fig.  13. 

HEAT.  A  form  of  energy.  A  vibratory  motion  impressed  on  the 
molecules  of  matter  by  the  action  of  any  form  of  energy.  A  wave 
motion  impressed  on  the  universal  ether  by  the  action  of  some  form 
of  energy. 

HEAT  UNIT.  The  quantity  of  heat  required  to  raise  a  unit  mass 
of  water  through  one  degree  of  the  thermometric  scale — the  cal- 
orie. There  are  a  number  of  different  heat  units.  The  most  im- 
portant are: 

The  British  Heat  Unit,  or  Thermal  Unit,  or  the  amount  of  heat 
required  to  raise  1  pound  of  water  1  degree  Fahr.  This  unit  repre- 
sents an  amount  of  work  equal  to  772  foot-pounds. 

The  Calorie,  or  the  amount  of  heat  required  to  raise  the  tempera- 
ture of  one  gramme  of  water  1  degree  C. 

The  Joule,  or  the  quantity  of  heat  developed  in  one  second  by 
the  passage  of  a  current  of  one  ampere  through  a  resistance  of  one 
ohm. 

1  joule  equals  .2407  calories. 

1  foot-pound  equals  1.356  joules. 

HENRY.  The  practical  unit  of  self-induction.  An  earth-quad- 
rant or  109  centimeters.  The  value  of  the  henry  as  adopted  by  the 
International  Electrical  Congress  of  1893,  at  Chicago.  The  value 
of  the  induction  in  a  circuit,  when  the  electromotive  force  induced  in 
the  circuit  in  one  International  volt,  and  the  inducing  current  varies 
at  the  rate  of  one  ampere  per  second. 

HIGH  FREQUENCY.  This  term  is  used  to  some  extent  as  de- 
nning high  commercial  frequencies  such  as  133  cycles  per  second. 
The  term  should  rather  be  used  to  define  frequencies  much  higher 

[31] 


Sec.  1  DICTIONARY 

than  those  in  commercial  use;  i.  e.,  frequencies  produced  by  light- 
ning discharges,  arcing  grounds,  etc. 

HIGH  POTENTIAL  CURRENT.  A  term  loosely  applied  for  a 
current  produced  by  high  electromotive  forces. 

HIGH  POTENTIAL  INSULATOR.  An  insulator  suitable  for 
use  on  high  potential  circuits. 

HIGH  TENSION  CIRCUIT.  A  circuit  employed  in  connection 
with  high  electric  pressures. 

HORSE-POWER.  A  commercial  unit  of  power,  or  rate-of-doing- 
work.  A  rate-of-doing-work  equal  to  33,000  pounds  raised  one  foot- 
per-minute,  or  550  pounds  raised  one  fpot-per-second.  A  rate-of- 
doing-work  equal  to  4.562  kilograms  raised  one  meter  per  minute. 

HORSE-POWER,  ELECTRIC.  Such  a  rate-of -doing  electrical 
work  as  is  equal  to  746  watts,  or  746  volt-coulombs  per  second. 

HORSE-POWER-HOUR.  A  unit  of  work  equal  to  the  work  done 
by  one  horse-power  acting  for  an  hour.  1,980,000  foot-pounds. 

HYDRO-ELECTRIC  SYSTEM.  An  electric  system  with  gen- 
erators driven  by  water-power. 

HYSTERESIS.  A  lagging  behind  of  magnetization  relatively  to 
magnetizing  force.  Apparent  molecular  friction  due  to  magnetic 
change  of  stress.  A  retardization  of  the  magnetizing  or  demagnet- 
izing effects  as  regards  the  causes  which  produce  them.  That  qual- 
ity of  a  para-magnetic  substance  by  virtue  of  which  energy  is  dissi- 
pated on  the  reversal  of  its  magnetization. 

HYSTERESIS  COEFFICIENT.  The  hysteretic  coefficient.  The 
energy  dissipated  in  a  cubic  centimeter  of  magnetic  material  by  a 
single  cyclic  reversal  of.  unit  magnetic  density. 

HYSTERETIC  CYCLE.  A  cycle  of  complete  magnetization  and 
reversal. 

HYSTERETIC  LAG.  The  lag  in  the  magnetization  of  a  trans- 
former due  to  hysteresis. 

I. 

I.     An  abbreviation  for  the  amount  of  current. 

I.  H.  P.     An  abbreviation  for  indicated  horse-power. 

I.2  R  LOSS.  The  loss  of  power  in  any  circuit  equal  to  the  square 
of  the  current  in  amperes  by  the  resistance  in  ohms. 

IMPEDANCE  COILS.  A  term  sometimes  applied  to  choking 
coils,  reactance  coils,  or  economy  coil. 

IMPEDANCE.  That  quantity  which  when  multiplied  with  the 
total  current  in  amperes  will  give  the  impressed  e.m.f.  in  volts. 

[32] 


DICTIONARY  Sec.  1 

IMPRESSED  ELECTROMOTIVE  FORCE.  The  electromotive 
force  brought  to  act  in  any  circuit  to  produce  a  current  therein. 
In  an  alternating-current  circuit,  the  electromotive  force  due  to  an 
impressed  source,  in  contradistinction  to  the  effective  electromotive 
force,  or  that  which  is  active  in  producing  current,  or  the  electro- 
motive forces  due  to,  or  opposed  to,  self  or  mutual  induction.  An 
applied  e.m.f.  as  distinguished  from  a  resultant,  or  wattless  e.m.f. 

INDIA  RUBBER.  A  resinous  substance  obtained  from  the  milky 
juices  of  a  tropical  tree. 

INDUCED  CURRENT.  When  by  any  means  whatever  the  total 
number  of  lines  of  force  passing  through  any  circuit  is  changed,  an 
electric  current  is  produced  in  that  circuit.  Such  a  current  is  called 
an  induced  current. 

INDUCED  ELECTROMOTIVE  FORCES,  e.m.f.'s  set  up  by 
electro-dynamic  induction. 

INDUCED  M.  M.  F.  Any  magnetomotive  force  produced  by 
induction.  The  aligned  or  structural  magnetomotive  force  as  dis- 
tinguished from  the  prime  magnetomotive  force. 

INDUCTANCE.  That  property,  in  virtue  of  which  a  finite  elec- 
tromotive force  impressed  on  a  circuit  does  not  immediately  gen- 
erate the  full  current  due  to  the  resistance  of  the  circuit,  and  which, 
when  the  electromotive  force  is  withdrawn,  requires  a  finite  time  for 
the  current  strength  to  fall  to  its  zero  value.  A  property,  by  virtue 
of  which  the  passage  of  an  electric  current  is  necessarily  accompanied 
by  the  absorption  of  electric  energy  in  producing  a  magnetic  field. 
A  constant  quantity  in  a  circuit  at  rest,  and  devoid  of  iron,  depend- 
ing only  upon  its  geometrical  arrangement,  and  usually  expressed 
in  henrys,  or  in  centimeters. 

INDUCTANCE  COIL.  An  impedance,  reactance,  or  choking  coil. 
A  coil  placed  in  a  circuit,  for  the  purpose  of  preventing  an  impulsive 
current-rush  in  that  circuit,  by  means  of  the  counter-electromotive 
force  developed  in  the  coil  on  being  magnetized. 

INDUCTION.  The  property  by  which  one  body  having  electrical 
or  magnetic  polarity  causes  or  induces  it,  in  another  body  or  another 
part  of  its  own  body  without  direct  contact. 

INDUCTION,  MAGNETIC.  The  production  of  magnetism  in  a 
magnetizable  substance  by  bringing  it  into  a  magnetic  field. 

INDUCTION,  MUTUAL.  Induction  produced  by  two  neighbor- 
ing circuits  on  each  other  by  the  mutual  interaction  of  their  magnetic 
fields. 

INDUCTION,  SELF.     (See  Self  Induction.) 

INDUCTIVE  CIRCUITS.  Circuits  containing  certain  types  of 
apparatus  and  known  as  inductive  circuits  have  the  property  of 
storing  up  a  part  of  the  energy  supplied  to  the  circuits  during  a 

2  [33] 


Sec.  1  DICTIONARY 

part  of  each  cycle,  and  restoring  this  energy  to  the  source  during 
the  remainder  of  the  cycle.  This  causes  the  reversal  of  current  to 
take  place  at  an  earlier  or  a  later  instant  that  the  reversal  of  yoltage, 
the  current  being  known  then  as  a  lagging  current.  During  the 
time  when  energy  is  being  delivered  to  the  circuit,  the  product  of 
voltage  and  current  is  positive ;  that  is,  the  voltage  and  the  current 
have  the  same  sign.  When  either  voltage  or  current  is  reversed 
with  respect  to  the  other  so  that  this  product  is  negative,  power  is 
being  returned,  by  the  circuit  to  the  source,  and  is  then  reckoned 
as  a  negative.  The  net  value  of  the  energy  delivered  to  the  circuit 
per  cycle  is  equal  to  the  difference  between  the  positive  and  the  nega- 
tive values  of  energy  in  the  two  periods  above  referred  to.  The 
average  value  of  the  power  for  a  given  value  of  voltage  and  current 
is  then  less  than  the  product  of  the  voltage  and  the  current  (the  volt- 
amperes)  and  may  have  any  value  between  the  value  of  the  volt- 
amperes  and  zero. 

INDUCTIVE  CIRCUIT.     Any  circuit  in  which  induction  occurs. 

INDUCTIVE  REACTANCE.  Reactance  due  to  self  induction  as 
distinguished  from  reactance  due  to  a  condenser. 

IN-PUT.  The  power  absorbed  by  any  machine  in  causing  it  to 
perform  a  certain  amount  of  work. 

INSTANTANEOUS  PEAK.  The  highest  value  reached  by  the 
quantity  under  consideration  as  measured  by  some  device  which 
indicated  high  actual  value  of  the  quantity  at  every  moment. 

INSULATE.  To  so  cover  or  protect  a  body  as  to  prevent  elec- 
tricity from  being  conducted  to  or  removed  from  it. 

INSULATED  WIRES.  Wires  provided  with  insulating  coverings 
or  coatings. 

INSULATING  JOINT.  A  joint  in  an  insulating  material  or 
covering  in  which  the  continuity  of  the  insulating  material  is  in- 
sured. 

INSULATING  VARNISH.  An  electric  varnish  formed  of  any 
good  insulating  material. 

INSULATION  RESISTANCE.  The  resistance  existing  between 
a  conductor  and  the  earth  or  between  two  conductors  in  a  circuit 
through  insulating  materials  lying  between  them.  A  term  applied 
to  the  resistance  of  the  insulating  material  of  a  covered  wire  or  con- 
ductor to  an  impressed  voltage  tending  to  produce  a  leakage  of 
current. 

INSULATOR,  ELECTRIC.  A  body  or  substance  which  offers 
such  resistance  to  the  passage  of  electric  current  that  it  is  used  to 
prevent  the  passage  of  current.  Any  device  employed  for  insulating 
a  wire  or  other  body. 

[34] 


DICTIONARY  Sec.  1 

INSULATOR  PIN.  The  device  by  which  an  insulator  is  attached 
to  a  bracket,  cross-arm,  or  support. 

IRON-CORE-LOSS.  The  hysteretic  and  Foucault  losses  due 
to  the  presence  of  an  iron  core. 

J. 

JOULE.  A  volt  coulomb  or  unit  of  electric  energy  or  work.  The 
amount  of  electric  work  required  to  raise  the  potential  of  one  coul- 
omb of  electricity  one  volt.  Ten  million  ergs. 

The  value  of  the  joule  as  adopted  by  the  International  Electrical 
Congress  of  1893,  at  Chicago.  A  value  equal  to  107  units  of  work 
of  the  C.G.S.  system  and  represented  with  sufficient  accuracy  for 
practical  purposes  by  the  energy  expended  in  one  second  by  one 
ampere  in  one  International  ohm. 

JOULE'S  LAW  OF  HEATING.  In  any  given  conductor  the 
heat  developed  by  an  electric  current  in  any  given  time  varies  di- 
rectly as  the  square  of  the  current,  and  as  the  resistance,  that  is,  the 
heat  varies  as  I2R.  Also  since  the  total  heat  varies  as  the  time,  the 
total  heat  is 

PR  T 

or,  if  expressed  in  calories 
PR^T 
4.2 

JUMPER.  A  temporary  shunt  or  short  circuit  put  around  a 
source,  lamp  or  receptive  device  on  a  series-connected  circuit,  to 
enable  it  to  be  readily  removed  or  repaired. 

K. 

kg.     An  abbreviation  for  kilogramme,  a  practical  unit  of  mass. 

kgm.  An  abbreviation  for  kilogramme  meter,  a  practical  unit 
of  the  moment  of  a  couple  or  of  work. 

kv-a.     An  abbreviation  for  kilo  volt-ampere. 

KAOLIN.  A  variety  of  white  clay  sometimes  employed  for  in- 
sulating purposes. 

KILO.     A  prefix  for  one  thousand  times. 
KILOVOLT.     One  thousand  volts. 

KILO  VOLT- AMPERE.  A  kilo  volt-ampere  is  1000  volt-amperes. 
A  volt-ampere  is  the  product  of  an  ampere  times  a  volt.  Its  energy 
equivalent  may  be  one  kilowatt  or  zero,  depending  upon  the  phase 
relation  between  the  current  and  voltage. 

KILOWATT.    One  thousand  watts. 

[  35  ] 


Sec.  1  DICTIONARY 

KILOWATT-HOUR.  The  amount  of  work  equal  to  that  per- 
formed by  one  kilowatt  maintained  steadily  for  one  hour.  An 
amount  of  work  equal  to  3,600,000  joules. 

KNIFE-SWITCH.  A  switch  which  is  opened  or  closed  by  the 
motion  of  a  knife  contact  between  parallel  contact  plates.  A  knife- 
edge  switch  or  knife  switch. 

L. 

LAGGING  CURRENT.  A  periodic  current  lagging  behind  the 
impressed  electromotive  force  which  produces  it. 

LAMINATED  CORE.  An  iron  core  that  has  been  sub-divided 
in  planes  parallel  to  its  magnetic  flux-paths,  in  order  to  avoid  the 
injurious  production  of  Foucault  or  eddy  currents. 

LAMINATION.     The  sub-division  of  an  iron  core  into  lamina. 

LEAD.  A  very  malleable  and  ductile  metal  of  low  tenacity  and 
high  specific  gravity.  Tensile  strength  1600  to  2400  pounds  per 
square  inch.  Elasticity  very  low,  and  the  metal  flows  under  a  very 
slight  strain.  Lead  dissolves  to  some  extent  in  pure  water,  but 
water  containing  carbonates  or  sulphates  forms  over  it  a  film  of  in- 
soluble salt  which  prevents  further  action.  Atomic  weight  206.9. 
Specific  gravity  11.07  to  11.44.  Melts  at  about  625°  F.;  softens 
and  becomes  pasty  at  617°  F. 

LEAD-ENCASED  CABLE.  A  cable  provided  with  a  sheathing 
or  coating  of  lead  on  its  external  surface. 

LEADING  CURRENT.  An  alternating  current  wave  or  com- 
ponent, in  advance  of  the  electromotive  force  producing  it. 

LEAKAGE  REACTANCE.  That  portion  of  the  reactance  of  any 
induction  apparatus  which  is  due  to  stray  flux. 

LEG  OF  CIRCUIT.  A  branch  of  a  bifurcated  or  divided  circuit. 
A  loop  or  offset  in  a  series  circuit. 

LENZ'S  LAW.  In  all  cases  of  induction  the  direction  of  the  in- 
duced current  is  such  as  to  oppose  the  motion  which  produces  it. 

LIGHTNING  ARRESTER.  A  device  by  means  of  which  the 
apparatus  placed  in  any  electric  circuit  is  protected  from  the  de- 
structive effects  of  a  flash  or  discharge  of  lightning. 

LIGHTNING  ROD.  A  rod,  strap,  wire  or  stranded  cable,  of  good 
conducting  material,  placed  on  the  outside  of  a  house  or  other  struc- 
ture, in  order  to  protect  it  from  the  effects  of  a  lightning  discharge. 

LINES  OF  FORCE.     Lines  of  magnetization. 

LINES  OF  MAGNETIZATION.  A  term  sometimes  applied  for 
lines  of  magnetic  induction.  A  term  sometimes  applied  to  those 

[36] 


DICTIONARY  Sec.  1 

portions  of  the  lines  of  magnetic  force  which  lie  within  the  mag- 
netized substance. 

LIVE  WIRE.  A  wire  through  which  current  is  passing.  A  wire 
connected  with  an  electric  pressure  or  source. 

LOAD.     The  work  thrown  on  any  machine. 

LOAD-FACTOR.  The  fraction  expressed  in  percent  obtained 
by  dividing  the  average  load  over  any  given  period  of  time  by  the 
maximum  load  during  the  same  period  of  time. 

LOGARITHM.  The  exponent,  or  the  power  to  which  it  is  neces- 
sary to  raise  a  fixed  number  called  the  base,  in  order  to  produce  a 
given  number. 

LOOP  TEST.  A  localization  test  for  a  fault  in  a  loop  of  two 
wires,  or  in  a  complete  metallic  circuit. 

LOW-POTENTIAL  SYSTEM.  In  the  National  Electric  Code  a 
system  having  a  pressure  less  than  550  and  more  than  10  volts. 


M. 

m.     A  symbol  for  strength  of  magnetic  pole. 

m.     An  abbreviation  for  meter,  a  practical  unit  of  length. 

M,  m.     An  abbreviation  for  mass. 

mm.     An  abbreviation  for  millimeter. 

m.m.f.     An  abbreviation  for  magnetomotive  force. 

MAGNETIC  FATIGUE.  (See  Fatigue  of  Iron  and  Steel,  Mag- 
netic.) 

MAGNETIC  FIELD.     (See  Field  Magnetic.) 

MAGNETIC  FLUX.  The  streamings  that  issue  from  and  return 
to  the  poles  of  a  magnet.  The  total  number  of  lines  of  magnetic 
force  in  any  magnetic  field.  The  magnetic  flow  that  passes  through 
any  magnetic  circuit. 

MAGNETIC  FLUX-PATHS.  Paths  taken  by  magnetic  flux  in 
any  magnetic  circuit. 

MAGNETIC  FORCE.  The  force  which  causes  the  attractions 
and  repulsions  of  magnetic  poles. 

MAGNETIC  INTENSITY.  Magnetic  flux-density.  The  quan- 
tity of  magnetic  flux  per-unit-of-area  of  normal  cross-section. 

MAGNETIC  SATURATION.  The  maximum  magnetization 
which  can  be  imparted  to  a  magnetic  substance.  The  condition  of 
iron  or  other  magnetic  substance,  when  its  intensity  of  magnetiza- 

[37] 


Sec.  1  DICTIONARY 

tion  is  so  great  that  it  fails  to  be  further  magnetized  by  any  mag- 
netizing force,  however  great. 

MAGNETIC  UNITS.  Units  based  on  the  force  exerted  between 
magnet  poles.  Units  employed  in  dealing  with  magnets  and  mag- 
netic phenomena.  The  magnetic  system  of  C.G.S.  electromagnetic 
units,  as  distinguished  from  the  electrostatic  system. 

MAGNETIZING  FORCE.  The  force  at  any  point  with  which  a 
unit  magnetic  pole  would  be  acted  on. 

MAINS.  In  a  parallel  system  of  distribution  the  conductors 
carrying  the  main  current,  and  to  which  translating  devices  are  con- 
nected. 

MASS.     Quantity  of  matter  contained  in  a  body. 

MAXIMUM  DEMAND.  The  maximum  demand  is  the  maxi- 
mum load  specified,  contracted  for  or  used,  expressed  in  terms  of 
power  as  kilowatts  or  horse-power. 

MAXWELL.     The  unit  of  magnetic  flux. 

MEAN  CURRENT.  The  time  average  of  a  current  strength. 
In  an  alternating-current  circuit,  the  time  average  of  a  current 
strength  without  regard  to  sign  or  direction. 

MEAN  ELECTROMOTIVE  FORCE.  The  average  electro- 
motive force.  In  an  alternating-current  circuit  the  time  average 
of  the  e.m.f.  without  regard  to  sign  or  direction. 

MECHANICAL  EQUIVALENT  OF  HEAT.  The  amount  of 
mechanical  energy  converted  into  heat  that  would  be  required  to 
raise  the  temperature  of  a  unit  mass  of  water  one  degree  of  the 
thermometric  scale.  The  quantity  of  energy  mechanically  equival- 
ent to  one  heat  unit.  (See  Heat  Unit.) 

MEGOHM.     One  million  ohms. 

MESSENGER  ROPE.  In  cable-work  a  rope  drive  f9r  operating 
a  drum  or  winch  at  a  distance.  A  rope  supporting  guide  sheaves. 

MHO.  The  unit  of  conductance.  Such  a  conductance  as  is 
equal  to  the  reciprocal  of  one  ohm.  A  unit  of  electric  conductance 
of  the  value  of  109  absolute  units. 

MICA.  A  refractory  mineral  substance  employed  as  an  insulator. 
A  double  silicate  of  alumina  or  magnesia  and  potash  or  soda. 

MICROFARAD.     One-millionth  of  a  farad. 

MICROMETER  WIRE-GAUGE.  A  sensitive  form  of  wire  gauge, 
usually  constructed  with  a  fine  thread  screw,  having  a  graduated 
head  for  close  measurements  of  wire  diameters. 

MICROHM.    The  millionth  of  an  ohm. 

[38] 


DICTIONARY  Sec.  1 

MIL.  A  unit  of  length  used  in  measuring  the  diameter  of  wires 
equal  to  the  one-thousandth  of  an  inch. 

MIL-FOOT.  A  resistance  standard  consisting  of  a  foot  of  wire, 
or  other  conducting  material,  one  mil  in  diameter.  A  standard  of 
comparison  of  resistivity  or  conductivity  of  wires. 

MILLI-AMPERE.    The  thousandth  of  an  ampere. 
MILLI-HENRY.     A  thousandth  part  of  a  henry. 
MILLI-VOLT.     The  thousandth  of  a  volt. 

MODULUS  OF  ELASTICITY.  The  ratio  of  the  simple  stress 
required  to  produce  a  small  elongation  or  compression  in  a  rod  of 
unit  area  of  normal  cross-section,  to  the  proportionate  change  of 
length  produced. 

MOISTURE-PROOF  INSULATION.  A  type  of  insulation  which 
is  not  strictly  water-proof,  but  which  is  capable  of  being  immersed 
for  a  short  time  without  suffering  serious  loss  of  insulation. 

MULTIPLE  CIRCUIT.     (See  Circuit  Multiple.) 

MULTIPLE-SERIES  CIRCUIT.  A  circuit  in  which  a  number  of 
separate  sources,  or  receptive  devices,  or  both,  are  connected  in  a 
number  of  separate  groups  in  series,  and  these  separate  groups  sub- 
sequently connected  in  multiple. 

MUTUAL  INDUCTION.     (See  Induction,  Mutual.) 

N. 

N.  Used  to  designate  the  number  of  turns  of  a  conductor  in 
electro-magnetic  equations  or  calculations.  Also  used  to  indicate 
the  number  of  revolutions  per  minute  (R.P.M.). 

n.     An  abbreviation  for  a  number. 

NEGATIVE  CONDUCTOR.  The  conductor  connected  to  the 
negative  terminal  of  an  electric  source. 

NEGATIVE  FEEDERS.  The  feeders  connecting  the  negative 
mains  with  the  negative  poles  of  the  generators. 

NEUTRAL  CONDUCTOR.  The  middle  wire  in  a  three  wire 
"Edison  system."  The  wire  from  the  common  point  of  connection 
of  the  phases  in  four  wire,  three  phase  and  five  wire,  two  phase 

systems. 

NEUTRAL  FEEDER.  In  a  three-wire  system,  a  feeder  connected 
with  the  neutral  bus-bar. 

NON-CONDUCTOR.  Any  substance  whose  conductivity  is  low, 
or  whose  electric  resistance  is  great. 

[  39  ] 


Sec.  1  DICTIONARY 

NON-INDUCTIVE  RESISTANCE.  A  resistance  devoid  of  self- 
induction. 

NORMAL  CURRENT.  The  current  strength  at  which  a  system 
or  apparatus  is  designed  to  be  operated. 

o. 

Q    An  abbreviation  for  ohm,  the  practical  unit  of  resistance, 
w    A  symbol  sometimes  employed  for  angular  velocity. 

OERSTED.  The  name  used  for  the  C.G.S.  unit  of  magnetic 
reluctance.  The  reluctance  offered  to  the  passage  of  magnetic  flux 
by  a  cubic  centimetre  of  air  when  measured  between  parallel  faces. 

OHM.  The  practical  unit  of  electric  resistance.  Such  a  re- 
sistance as  would  limit  the  flow  of  electricity  under  an  electromotive 
force  of  one  volt,  to  a- current  of  one  ampere,  or  one-coulomb-per- 
second.  The  value  of  the  ohm  as  adopted  by  the  International 
Electrical  Congress  of  1893,  at  Chicago,  is  a  value  of  the  ohm  equal 
to  109  units  of  resistance  of  the  C.G.S.  system  of  electro-magnetic 
units,  and  represented  by  the  resistance  offered  to  an  unvarying 
electric  current  by  a  column  of  mercury  at  the  temperature  of 
melting  ice,  14.4521  grammes  in  mass,  of  a  constant  cross-sectional 
area,  and  of  the  length  of  106.3  centimeters. 

OHMIC  DROP.  The  drop  in  pressure  due  to  the  ohmic  resist- 
ance. 

OHMIC  RESISTANCE.  The  true  resistance  of  a  conductor  due 
to  its  dimensions  and  conductivity,  as  distinguished  from  the  spuri- 
ous resistance  produced  by  counter-electromotive  force.  A  re- 
sistance such  as  would  be  measurable  in  ohms  by  the  usual  methods 
of  continuous-current  measurement. 

OHM'S  LAW.  The  law  of  non-varying  current  strength  in  a 
circuit  not  subject  to  variation.  The  strength  of  a  continuous  cur- 
rent is  directly  proportional  to  the  difference  of  potential  or  electro- 
motive force  in  the  circuit  and  inversely  proportional  to  the  resist- 
ance of  the  circuit,  i.  e.,  is  equal  to  the  quotient  arising  from  dividing 
the  electromotive  force  by  the  resistance. 

Ohm's  law  is  expressed  algebraically  thus: 

E  E 

I=~R~;  or  E=IR; or  R=T~ 

If  the  electromotive  force  is  given  in  volts,  and  the  resistance  in 
ohms,  the  formula  will  give  the  current  strength  directly  in  amperes. 

The  current  in  amperes  is  equal  to  the  electromotive  force  in  volts 
divided  by  the  resistance  in  ohms. 

The  electromotive  force  in  volts  is  equal  to  the  product  of  the  cur- 
rent in  amperes  and  the  resistance  in  ohms. 

[40] 


DICTIONARY  Sec.  1 

The  resistance  in  ohms  is  equal  to  the  electromotive  force  in  volts 
divided  by  the  current  in  amperes. 

OPEN  CIRCUIT.  A  broken  circuit,  or  a  circuit  whose  conduct- 
ing continuity  is  broken. 

OSCILLATORY  CURRENT.  A  current  which  oscillates  or  per- 
forms periodic  vibrations  usually  of  diminishing  amplitude. 

OVERHEAD  CONDUCTOR.     An  aerial  conductor. 

P. 

PAGE  EFFECT.  Faint  sounds  produced  when  a  piece  of  iron  is 
rapidly  magnetized  and  demagnetized. 

PAPER  CABLE.  A  paper-insulated  cable.  A  cable  in  which 
paper  is  the  solid  insulator  employed. 

PARAFFINE.  A  solid  hydro-carbon  possessing  high  insulating 
powers. 

PARALLEL  CIRCUIT.  A  term  sometimes  used  for  multiple 
circuit. 

PEAK-LOAD.  The  highest  average  load  carried  for  any  specified 
period. 

NOTE.  The  term  may  be  preceded  by  the  qualifying  terms 
"hourly,"  " daily,"  "monthly,"  "yearly,"  etc. 

PEAK.     The  highest  load  carried  for  any  specified  period. 

PERCENTAGE  CONDUCTIVITY  OF  WIRE.  The  conductiv- 
ity of  a  wire  in  terms  of  the  conductivity  of  pure  copper.  The  con- 
ductivity of  a  particular  copper  wire  compared  with  the  conductivity 
of  a  standard  wire  of  the  same  dimensions.  The  conductivity  of  a 
wire  referred  to  Matthiessen's  standard  of  conductivity  for  copper. 

PERIODIC  FUNCTION.  A  periodic  function  is  one  which  re- 
pea.ts  itself  after  a  definite  time  or  period.  If  any  number  of  simple 
sine  functions  of  the  same  period  be  added,  the  resultant  sum  will 
be  a  simple  sine  function  of  the  same  period.  This  is  shown  in  Fig. 
14  for  the  addition  of  two  simple  sine  functions  or  sine  waves,  and 
it  is  evident  that,  if  true  for  the  addition  of  two,  it  is  true  for  the 
addition  of  any  number  of  simple  sine  functions.  "An  example  of 
the  addition  of  two  simple  sine  functions  of  the  same  period  is  shown 
in  Fig.  15.  The  resultant  curve,  represented  by  the  heavy  line,  is 
likewise  a  sine  curve. 

PERIODICITY.  The  number  of  periods  executed  per  second  by 
a  periodically  alternating  quantity.  The  number  of  cycles  executed 
in  unit  time  by  an  alternating  current.  The  frequency  of  an  alter- 
nating current. 

PERMITTANCE.  Electrostatic  capacity.  The  capability  of  a 
condenser  or  dielectric  to  hold  a  charge. 

[41] 


Sec.  1 


DICTIONARY 


PETTICOAT  INSULATOR.     An  insulator  provided  with  a  deep 
internal  groove,  around  its  lower  extremity  or  stalk.     A  line  wire 


FIG.  14. — Summation  of  Two  Simple  Sine  Waves  to  Form  a  Resultant  Sine  Wave. 


vertical  insulator  provided  with  an  insulating  inverted  cup  having  a 
form  resembling  a  petticoat. 


360° 


FIG.  15. — Diagram  showing  the  Formation  of    a  Resultant  Sine  Wave  from 
Two  Simple  Sine  Waves. 

PHASE.  The  distance,  usually  in  angular  measure,  of  the  base 
of  any  ordinate  of  an  alternating  wave  from  any  chosen  point  on 
the  time  axis,  is  called  the  phase  of  this  ordinate  with  respect  to  this 

[42] 


DICTIONARY 


Sec.  1 


point.  In  the  case  of  a  sinusoidal  alternating  quantity  the  phase  at 
any  instant  may  be  represented  by  the  corresponding  position  of  a 
line  or  vector  revolving  about  a  point  with  such  an  angular  velocity 
(oj=27rf)  that  its  projection  at  each  instant  upon  a  convenient 
reference  line  is  proportional  to  the  value  of  the  quantity  at  that 
instant. 

PHASE  ANGLE.  In  alternating  current  systems  two  or  more 
currents  or  e.m.f.'s  which  do  not  come  to  their  maximum  values  at 
the  same  instant  are  said  to  be  out  of  phase,  or  to  have  a  phase  dif- 
ference, and  the  angle  between  the  vectors  which  represent  these 
currents  or  e.m.f.'s  is  called  a  phase  angle.  If  it  is  measured  for- 
ward, in  the  direction  of  rotation,  the  angle  is  called  the  angle  of 


FIG.  16. — Diagram  showing  the  Phase  Angles  between  Three  Distinct  e.m.f.'s. 
and  their  Vector  Representations. 


lead,  and  if  measured  against  the  direction  the  angle  is  called  the 
angle  of  lag.     (Fig.  16.) 

PHASE  DIFFERENCE:   LEAD  and  LAG.     When  corresponding 
cyclic  values  of  two  sinusoidal  alternating  quantities  of  the  same  fre- 

auency  occur  at  different  instants,  the  two  quantities  are  said  to 
iffer  in  phase  by  the  angle  between  their  nearest  corresponding 
values,  e.g.,  their  nearest  ascending  zeros  or  positive  maxima.     That 
quantity  whose  maximum  value  occurs  first  in  time  is  said  to  lead 
the  other,  and  the  latter  is  said  to  lag  behind  the  former. 

PINS.     Wooden  or  steel  pegs  for  supporting  pole  line  insulators. 

PLANE  VECTOR.     A  quantity  which  possesses  not  only  magni- 
tude but  also  direction  in  a  single  plane. 

[43] 


Sec.  1  DICTIONARY 

PLATINUM.  A  heavy  refractory  and  not  readily  oxydizable 
metal  of  a  tin-white  color. 

PLUMBAGO.     An  allotropic  modification  of  carbon. 
POLE  GUYS.     A  guy  employed  for  stiffening  a  pole. 

POLE  STEPS.  Steps  permanently  fastened  to  a  wood  or  iron 
pole  to  facilitate  climbing. 

POLYPHASE.     Possessing  more  than  a  single  phase. 

POLYPHASE  CIRCUITS.  The  circuits  employed  in  polyphase  - 
current  distribution. 

POLYPHASE  CURRENTS.  Currents  differing  in  phase  from 
one  another  by  a  definite  amount,  and  suitable  for  the  operation  of 
polyphase  motors  or  similar  apparatus. 

PpLYPHASE  TRANSFORMER.  A  transformer  suitable  for 
use  in  connection  with  polyphase  circuits. 

POLYPHASE  TRANSMISSION.  Transmission  of  power  by 
means  of  polyphase  currents. 

PORCELAIN.  A  variety  of  insulating  substance,  made  from 
clay. 

POSITIVE  WIRE.  The  wire  connected  with  the  positive  pole 
of  a  source. 

POTENTIAL,  ELECTRIC.     The  power  of  doing  electric  work.  ' 
Electric  level. 

POTENTIAL  ENERGY.  Stored  energy.  Capability  of  doing 
work.  Energy,  possessing  the  power  or  potency  of  doing  work  but 
not  actually  performing  such  work. 

POWER.  Rate-of-doing-work,  expressible  in  watts,  joules-per- 
second,  foot  pounds-per-hour,  etc. 

POWER  CIRCUITS.  Circuits  employed  for  the  electric  trans- 
mission of  power. 

POWER-FACTOR.  The  ratio  of  the  power  (cyclic  average)  to 
the  volt-amperes.  In  the  case  of  sinusoidal  current  and  voltage 
the  power-factor  is  equal  to  the  cosine  of  the  difference  in  phase 
between  them. 

PRIMARY.  That  winding  of  a  transformer  which  directly  re- 
ceives power.  The  term  is  to  be  preceded,  in  the  case  of  transform- 
ers, by  the  words  "high  voltage"  or  "low  voltage." 

PRIMARY  COIL  OF  TRANSFORMER.  That  coil  of  an  in- 
duction coil  or  transformer  on  which  the  primary  electromotive 
force  is  impressed.  The  coil  which  receives  energy  prior  to  trans- 
formation. 


DICTIONARY  Sec.  1 

PRIMARY  CURRENTS.  Currents  flowing  in  a  primary  circuit, 
as  distinguished  from  currents  flowing  in  a  secondary  circuit. 

PRIMARY  ELECTROMOTIVE  FORCE.  The  electromotive 
force  applied  to  the  primary  coil  of  a  transformer. 

PULSATING  CURRENT  is  a  current  which  pulsates  regularly 
in  magnitude.  As  ordinarily  employed,  the  term  refers  to  unidirec- 
tional current. 

Q. 

QUADRATURE.  A  term  applied  to  express  the  fact  that  one 
simple-harmonic  quantity  lags  90°  behind  another. 

QUANTITY,  ELECTRIC.  The  amount  of  electricity  present  in 
any  current  or  charge. 

QUARTER  PHASE.  A  term  implying  the  supplying  of  power 
through  two  circuits.  The  vector  angle  of  this  voltage  is  90  degrees. 
This  term  is  used  at  times  instead  of  the  term  "two-phase." 

QUARTER-PHASE  SYSTEM.  A  two-phase  system  of  alter- 
nating-current distribution  employing  two  currents  dephased  by  a 
quarter  period. 

R. 

r.m.s.  A  term  sometimes  used  for  the  square  root  of  the  mean 
square  of  the  current.  The  effective  current  or  voltage. 

RADIAN.  A  unit  angle.  An  angle  whose  circular  arc  is  equal  in 
length  to  its  radius;  or,  approximately  57°  17'  45". 

RADIAN-PER  SECOND.  A  unit  of  angular  velocity  of  a  rotat- 
ing body. 

RATIO  OF  TRANSFORMATION.  The  ratio  between  the  elec- 
tromotive force  produced  at  the  secondary  terminals  of  an  induction 
coil  or  transformer,  and  the  electromotive  force  impressed  on  the 
primary  terminals. 

REACTANCE,  INDUCTIVE.  The  inductance  of  a  coil  or  circuit 
multiplied  by  the  angular  velocity  of  the  sinusoidal  current  passing 
through  it,  or  expressed  by  the  formula  X  =  2-n-  f  L  =  coL,  where  co  = 
2irf,  f  is  the  frequency  in  cycles  per  second,  and  L  is  the  coefficient 
of  self-induction. 

A  quantity  whose  square  added  to  the  square  of  the  resistance 
gives  the  square  of  the  impedance,  in  a  simple  harmonic  current  cir- 
cuit. 

REACTANCE  FACTOR.  The  ratio  of  the  reactance  of  a  coil, 
or  circuit,  to  its  ohmic  resistance. 

REACTIVE  DROP.  The  drop  in  a  circuit  or  conductor  due  to 
its  reactance  as  distinguished  from  the  drop  due  to  its  ohmic  re- 
sistance. 

[45] 


Sec.  1  DICTIONARY 

REACTIVE  ELECTROMOTIVE  FORCE.  In  an  alternating 
current  circuit,  that  component  of  the  electromotive  force  that  is  in 
quadrature  with  the  current  and  is  employed  in  balancing  the 
counter  e.m.f.  of  inductance. 

REACTIVE  FACTOR.  The  ratio  of  the  wattless  volt-amperes 
to  the  total  volt-amperes. 

REGULATION.  The  regulation  of  a  machine  or  apparatus  in 
regard  to  some  characteristic  quantity,  such  as  current  or  terminal 
voltage,  is  the  ratio  of  deviation  of  that  quantity  from  its  normal 
value  at  rated-load  to  the  normal  rated-load  value.  Sometimes 
called  inherent  regulation. 

RELUCTANCE.  A  term  applied  to  magnetic  resistance.  In  a 
magnetic  circuit  the  ratio  of  the  m.m.f.  to  the  total  magnetic  flux. 

RELUCTIVITY.     The  specific  magnetic  resistance  of  a  medium. 

RESIDUAL  MAGNETISM.  The  magnetism  remaining  in  a 
core  of  an  electromagnet  on  the  opening  of  the  magnetizing  circuit. 
The  small  amount  of  magnetism  retained  by  soft  iron  when  removed 
from  any  magnetic  field. 

RESIN.  A  general  term  applied  to  a  variety  of  dried  juices  of 
vegetable  origin. 

RESISTANCE.  The  quality  of  an  electrical  conductor  by  virtue 
of  which  it  opposes  an  electric  current.  The  unit  of  resistance  is 
the  ohm. 

Resistance  is  that  attribute  of  a  conductor  or  of  a  circuit  which 
determines  the  strength  of  the  electric  current  that  can  be  sent 
through  the  conductor  or  the  circuit,  on  which  a  constant  difference 
of  potential  is  maintained,  as  shown  by  Ohm's  law.  The  resistance 
of  a  given  conductor  is  always  constant  at  the  same  temperature, 
irrespective  of  the  strength  of  current  flowing  through  it  or  the  elec- 
tromotive force  of  the  current,  and  the  resistance  of  a  given  con- 
ductor increases  as  the  length  of  the  conductor  increases;  that  is, 
the  resistance  of  a  conductor  is  directly  proportional  to  its  length. 
Also  the  resistance  of  a  conductor  varies  inversely  as  its  sectional 
area,  or  the  resistance  of  a  conductor  of  circular  cross  section  is 
inversely  proportional  to  the  square  of  its  diameter. 

The  combined  resistance  of  several  resistances  in  parallel  may  be 
found  by  taking  the  reciprocal  of  the  sum  of  the  reciprocals  of  the 
individual  resistances  of  the  branch  circuits.  This  law  follows  from 
the  law  of  conductance,  which  states  that  the  combined  conductance 
of  a  parallel  branch  circuit  is  equal  to  the  sum  of  the  conductances 
of  the  branches,  and  since  the  resistance  is  equal  to  the  reciprocal 
of  the  conductance,  the  reciprocal  law  holds  true,  as  above  stated. 

RESISTIVITY.  The  specific  resistance  of  a  substance  referred 
to  the  resistance  of  a  cube  of  unit  volume.  Specific  resistance,  or  the 
inverse  of  specific  conductivity. 

[46] 


DICTIONARY  Sec.  1 

RESONANCE.  In  a  circuit  containing  both  inductance  and 
capacity,  the  neutralization  or  annulment  of  inductance-reactance 
by  capacity-reactance,  whereby  the  impedance  of  the  circuit  or 
branch  is  reduced  to  the  ohmic  resistance.  In  an  alternating-cur- 
rent circuit,  the  attunement  of  a  circuit,  containing  a  condenser 
to  the  same  natural  undamped  frequency  of  oscillation  as  the  fre- 
quency of  impressed  e.m.f.  whereby  the  circuit  responds  to  this 
frequency  more  than  to  any  other.  In  an  alternating  current  cir- 
cuit, the  annulment  of  inductance-reactance  by  capacity-reactance, 
whereby  the  impedance  of  the  circuit  is  not  only  reduced  to  its  ohmic 
resistance,  but  its  current  is  in  phase  with  its  impressed  e.m.f. 

RESULTANT  MAGNETIC  FIELD.  A  single  magnetic  field 
produced  by  two  or  more  co-existing  magnetic  fields. 

RIGHT-HANDED  ROTATION.  A  direction  of  rotation  which 
is  the  same  as  that  of  the  hands  of  a  watch,  when  one  looks  directly 
at  the  face  of  the  watch.  Negative  rotation. 

ROOT-MEAN-SQUARE  or  EFFECTIVE  VALUE.  The  square 
root  of  the  mean  of  the  squares  of  the  instantaneous  values  for  one 
complete  cycle.  It  is  usually  abbreviated  r.m.s.  Unless  otherwise 
specified  the  numerical  value  of  an  alternating  current  (or  e.m.f.) 
refers  to  its  r.m.s.  value.  The  r.m.s.  value  of  a  sinusoidal  wave  is 
equal  to  its  maximum  value  divided  by  \rz. 

s. 

S.W.G.    An  abbreviation  for  Stubb's  wire  gauge. 

SADDLE  BRACKET.  A  bracket  holding  an  insulator  and  fast- 
ened to  the  top  of  a  pole. 

SAFETY  FUSE.  A  wire,  bar,  plate  or  strip  of  readily  fusible 
metal,  capable  of  conducting,  without  fusing,  the  current  ordinarily 
employed  on  the  circuit,  but  which  fuses  and  thus  automatically 
breaks  the  circuit  on  the  passage  of  an  abnormally  strong  current. 

SAG  OF  CONDUCTOR  OR  LINE  WIRE.  The  dip  of  an  aerial 
wire  or  conductor,  between  two  adjacent  supports,  due  to  its  weight. 

SECONDARY  AMPERE-TURNS.  Ampere-turns  in  the  second- 
ary of  a  transformer  or  induction  coil. 

SECONDARY.  That  portion  of  a  transformer  which  receives 
power  by  induction.  The  term  is  to  be  preceded  by  the  same  words 
as  in  the  case  of  "primary." 

SECONDARY  COIL  OF  TRANSFORMER.  The  coil  of  a  trans- 
former into  which  energy  is  transferred  from  the  primary  line  and 
primary  coil  by  induction. 

SECONDARY  CURRENTS.  The  currents  produced  in  the 
secondary  of  a  transformer.  The  currents  produced  by  secondary 
batteries.  Currents  in  any  secondary  circuit. 

147] 


Sec.  1  DICTIONARY 

SECONDARY  RESISTANCE.  The  resistance  of  a  secondary 
coil  or  circuit. 

SECONDARY  WINDING  is  that  winding  of  a  transformer  which 
receives  power  from  the  primary  by  induction. 

NOTE:  The  terms  "High-tension  winding"  and  "Low-tension 
winding"  are  suitable  for  distinguishing  between  the  windings  of  a 
transformer  where  the  relations  of  the  apparatus  to  the  source  of 
power  are  not  involved. 

SELF-INDUCTION.     (See  Induction,  Self.) 
SERIES  CIRCUIT.     (See  Circuit,  Series.) 

SERIES  DISTRIBUTION.  A  distribution  of  electric  energy  in 
which  the  receptive  devices  are  placed  one  after  another  in  succes- 
sion upon  a  single  conductor,  extending  throughout  the  entire  cir- 
cuit from  pole  to  pole. 

SERIES-MULTIPLE  CIRCUIT.  A  compound  circuit  in  which 
a  number  of  separate  sources,  or  separate  electro-receptive  devices, 
or  both,  are  connected  in  a  number  of  separate  groups  in  multiple, 
and  these  separate  groups  subsequently  connected  in  series. 

SERVICE  WIRES.  The  wires  which  lead  into  a  building  and 
which  are  connected  to  the  supply  mains  or  supply  circuits.  The 
wires  through  which  service  is  given  to  a  consumer.  Delivery 
wires. 

SHELLAC.  A  resinous  substance  obtained  from  the  roots  and 
branches  of  certain  tropical  plants,  which  possesses  high  insulating 
powers,  and  high  specific  inductive  capacity. 

SHORT  CIRCUIT.  A  shunt  or  by-path  of  negligible  or  com- 
paratively small  resistance,  placed  around  any  part  of  an  electric 
circuit  through  which  so  much  of  the  current  passes  as  to  virtually 
cut  out  the  parts  of  the  circuit  to  which  it  acts  as  a  shunt.  An 
accidental  direct  connection  between  the  mains  or  main  terminals  of 
a  dynamo  or  system  producing  a  heavy  overload  of  current. 

SIMPLE  HARMONIC  ELECTROMOTIVE  FpRCE.  An  electro- 
motive force  whose  value  varies  directly  as  the  sine  or  cosine  of  the 
angle  which  its  rotating  vector  makes  with  a  fixed  axis. 

SINE.  One  of  the  trigonometrical  functions.  The  ratio  of  the 
vertical  leg  of  a  right-angle  triangle  to  the  hypotenuse,  in  which  the 
hypotenuse  is  the  radius  vector,  and  the  angle  between  the  base  and 
the  hypotenuse  the  angle  whose  sine  is  considered. 

SINE  LAW.  A  law  of  magnitude  defined  by  the  sines  of  angles. 
A  magnitude  which  follows  the  sines  of  successive  angles. 

SINGLE-PHASE.  A  term  characterizing  a  circuit  energized  by  a 
single  alternating  e.m.f.  Such  a  circuit  is  usually  supplied  through 
two  wires.  The  currents  in  these  two  wires  counted  positively  out- 
wards from  the  source,  differ  in  phase  by  180  degrees  or  half  a  cycle. 

[48] 


DICTIONARY  Sec.  1 

SINGLE-POLE  CUT-OUT.  A  cut-out  by  means  of  which  the 
circuit  is  broken  or  cut  in  one  of  the  two  leads  only. 

SINUSOIDAL  ALTERNATING  ELECTROMOTIVE  FORCES. 

Alternating  electromotive  forces  whose  variations  in  strength  are 
correctly  represented  by  a  sinusoidal  curve. 

SINUSOIDAL  CURVE.  A  curve  of  sines.  A  curve  which  to 
rectangular  co-ordinates  has  an  ordinate  at  each  point  proportionate 
to  the  sine  of  an  angle  proportionate  to  the  abscissa. 

SKIN  EFFECT.  The  tendency  of  rapidly  alternating  currents 
to  avoid  the  central  portions  of  solid  conductors  and  flow,  for  the 
greater  part,  through  the  superficial  portions. 

SLEEVE  JOINT.  A  junction  of  the  ends  of  conducting  wires 
obtained  by  passing  them  through  tubes,  and  subsequently  twisting 
and  soldering. 

SOFT  DRAWN  COPPER  WIRE.  Copper  wire  that  is  softened 
by  annealing  after  being  drawn. 

SPECIFIC  CONDUCTIVITY.  The  particular  conductivity  of  a 
substance  for  electricity.  Conductivity  with  reference  to  Matth- 
iessen's  standard  conductivity. 

SPECIFIC  INDUCTIVE  CAPACITY.  The  ability  of  a  dielectric 
to  permit  induction  to  take  place  through  its  mass  as  compared  with 
the  ability  possessed  by  a  vacuous  space  of  the  same  dimensions, 
under  precisely  the  same  conditions.  The  relative  power  of  bodies 
for  transmitting  electrostatic  stresses  and  strains,  analogous  to 
permeability  in  metals.  The  ratio  of  the  capacity  of  a  condenser 
whose  coatings  are  separated  by  a  dielectric  of  a  given  substance,  to 
the  capacity  of  a  similar  condenser,  whose  plates  are  separated  by  a 
vacuum. 

SPECIFIC  RESISTANCE.  The  particular  resistance  a  substance 
offers  to  the  passage  of  electricity  through  it,  compared  with  the 
resistance  of  some  standard  substance.  In  absolute  measurements, 
the  resistance  in  absolute  units  between  opposed  faces  of  a  centi- 
metre cube  of  a  given  substance.  In  the  practical  system,  the  above 
resistance  in  ohms. 

SPELTER.  A  name  sometimes  given  to  commercial  zinc.  (See 
Zinc.) 

SPLICING  SLEEVE.  A  tube  of  conducting  material  employed 
for  covering  a  splice  in  a  conducting  wire. 

SPLIT  PHASE.  A  difference  produced  between  the  phases  of 
two  or  more  alternating  currents  into  which  a  uniphase  alternating 
current  has  divided. 

SQUARE  MIL.  A  unit  of  area  employed  in  measuring  the  areas 
of  cross-section  of  wires,  equal  to  .000001  square  inch.  A  unit  of 
area  equal  to  1.2732  circular  mils. 

[49] 


Sec.  1  DICTIONARY 

STAR  THREE-PHASE  SYSTEM.  A  system  in  which  all  three 
phase  windings  are  connected  together  at  a  common  point  or  neutral 
point,  and  the  three  free  ends  connected  to  the  circuit. 

STATIC  DISCHARGE.  A  name  sometimes  given  to  a  disruptive 
discharge. 

STATIC  ELECTRICITY.  A  term  applied  to  electricity  produced 
by  friction. 

STEP-DOWN  TRANSFORMER.  A  transformer  in  which  a 
small  current  of  comparatively  great  difference  of  potential  is  con- 
verted into  a  large  current  of  comparatively  small  difference  of 
potential. 

STEP-UP  TRANSFORMER.  A  transformer  in  which  a  large 
current  of  comparatively  small  difference  of  potential  is  converted 
into  a  small  current  of  comparatively  great  difference  of  potential. 

STRAIN.     Any  change  of  size  or  shape,  any  deformation. 

STRAIN  INSULATOR.  An  insulator  used  for  the  double  pur- 
pose of  taking  the  mechanical  strain  at  a  bend  or  at  the  end  of  a 
conductor,  and  also  insulating  the  same  electrically. 

STRANDED  CONDUCTOR.  A  conductor  formed  of  a  number 
of  smaller  interlaced  or  twisted  conductors,  either  for  the  purpose 
of  reducing  self-induction,  or  eddy  currents,  or  for  increasing  its 
flexibility. 

STRAY  CURRENTS.  A  term  sometimes  used  for  eddy  currents. 
Also  currents  that  leave  their  normal  or  proper  path  such  as  earth 
currents  of  ground  return  feeders. 

STRAY  FIELD.  Leakage  magnetic  flux.  That  portion  of  a 
magnetic  field  which  does  not  pass  through  an  armature  or  other 
magneto-receptive  device. 

STRENGTH  OF  CURRENT.     (See  Current  Strength.) 

STRESS.  Any  action  between  two  bodies  that  causes  a  strain, 
or  deformation. 

SUPPLY  MAINS.  A  term  sometimes  applied  to  the  mains  in  a 
system  of  incandescent  light  or  power  distribution. 

SURFACE  DENSITY.  The  quantity  of  electricity-per-unit-of- 
area  at  any  point  on  a  charged  surface. 

SURGING  DISCHARGE.  A  discharge  accompanied  by  electric 
surgings.  An  oscillatory  discharge. 

SURGINGS,  ELECTRIC.  Electric  oscillations  set  up  in  a  con- 
ductor that  is  undergoing  rapid  discharging,  or  in  neighboring  con- 
ductors that  are  being  rapidly  charged  and  discharged.  Electric 
oscillations,  direct  or  induced. 

SYNCHRONISM.  Unison  of  frequencies  in  alternating-current 
systems  or  apparatus.  Generally,  the  co-periodicity  and  co-phase 

[50] 


DICTIONARY  Sec.  1 

of  two  periodically  recurring  events.  The  coincidence  in  cyclic 
recurrence  of  two  or  more  periodic  variables,  without  regard  to 
amplitude. 

SYNCHRONO  SCOPE.  A  synchronizing  device  which,  in  ad- 
dition to  indicating  synchronism,  shows  whether  the  machine  is 
synchronized  fast  or  slow. 

T. 

TANGENT.  The  tangent  of  any  angle  may  be  found  by  con- 
structing a  right  triangle  in  which  the  angle  or  its  supplement  is  one 
of  the  acute  angles  of  the  triangle.  By  dividing  the  opposite  side 
of  the  triangle  by  the  adjacent  side,  the  tangent  of  the  angle  is 
obtained.  Also 

Sine0 
Tangent  0  = 


TAP.     A  conductor  attached  as  a  shunt  to  a  larger  conductor. 
A  derived  circuit  for  carrying  off  a  share  of  the  main  current. 


FIG.  17. — Relation  of  the  Waves  of  Current,  or  e.m.f.'s.,  in  a  Three-phase 
System. 

TEMPERATURE.     State  of  matter  in  respect  to  heat. 

TEMPERATURE  COEFFICIENT.  A  coefficient  of  variation  in 
a  quantity,  per  degree  of  change  in  temperature.  The  coefficient 
by  which  a  change  of  temperature  must  be  multiplied  in  order  to 
arrive  at  the  change  in  a  quantity  due  to  the  change  of  temperature. 

TERMINAL  VOLTAGE.  The  voltage  between  the  poles  at  the 
source  of  the  e.  m.  f . 

THREE-PHASE.  A  term  characterizing  the  combination  of 
three  circuits  energized  by  alternating  e.m.f.'s.  which  differ  in  phase 
by  one-third  of  a  cycle;  i.  e.,  120  degrees.  (Fig.  17.) 

[51] 


Sec.  1  DICTIONARY 

THREE-PHASE  TRANSFORMER.  A  transformer  constructed 
for  changing  the  ratios  of  voltages  and  currents  of  a  three-phase 
system. 

THREE-PHASE  TRANSMISSION.  Transmission  by  means  of 
three-phase  currents. 

THREE-WIRE  CIRCUIT.  A  circuit  employed  in  a  three-wire 
system.  A  three-wire  two  phase  system.  A  three-wire  three  phase 
system. 

THREE-WIRE  MAINS.  The  mains  employed  in  a  three-wire 
system  of  distribution. 

THREE- WIRE  SYSTEM.  A  system  of  electric  distribution  for 
lamps  or  other  multiple-connected  translating  devices,  in  which  three 
conductors  are  employed  in  connection  with  two  dynamos,  or  parts 
of  transformers  connected  in  series,  the  central  or  neutral  conductor 
being  connected  to  the  junction  of  this  apparatus,  and  the  two  othe 
conductors  to  the  remaining  free  terminal  of  each. 

TIE- WIRE.  Binding  wire  of  an  insulator.  Wire  which  binds  an 
overhead  wire  to  the  groove  of  its  insulator. 

TIME-CONSTANT  OF  CIRCUIT.  The  time  in  which  a  current 
will  fall  in  a  circuit  when  the  e.m.f.  is  suddenly  removed,  in  a  ratio 
whose  Naperian  logarithm  is  unity.  The  ratio  of  the  inductance 
of  a  circuit  to  its  resistance. 

TIME  SWITCH.  A  switch  arranged  to  open  or  close  a  circuit 
at  a  certain  time  or  after  the  lapse  of  a  certain  time. 

TRANSFORMER.  A  stationary  piece  of  apparatus  for  trans- 
forming, by  electro-magnetic  induction,  power  from  one  circuit  to 
another,  or  for  changing,  through  such  transformation,  the  values  of 
the  electromotive  force  or  current. 

TRANSFORMER-BALANCER.     An  auto-transformer  for  divid 
ing  a  voltage  in  constant  proportions,  and  usually  into  two  equal 
portions. 

TRANSFORMER  STAMPINGS.  Sheet  steel  stampings  of  such 
shape  as  is  suitable  for  building  up  the  laminated  core  of  a  trans- 
former. 

TRANSMISSION  CIRCUIT,  ELECTRIC.  The  circuit  em- 
ployed to  receive  the  apparatus  necessary  in  any  transfer  of  electric 
energy  from  the  generators  to  the  receptive  devices.  In  alternating- 
current  constant-potential  transmission  circuits  the  following  average 
voltages  are  in  general  use:  6,600,  11,000,  22,000,  33,000,  44,000, 
66,000,  88,000,  110,000. 

TRANSMISSION,  ELECTRIC.  The  transference  of  energy 
from  one  point  to  another  by  means  of  electric  currents. 

[52] 


DICTIONARY 


Sec.  1 


TRANSPOSING.  A  device  for  avoiding  the  bad  effects  of 
mutual  induction  by  alternately  crossing  equal  lengths  of  consecutive 
sections  of  the  line. 

TRIPLE  PETTICOAT  INSULATOR.  An  aerial  line  insulator 
having  three  discs  or  petticoats. 

TWO-PHASE.  A  term  characterizing  the  combination  of  two 
circuits  energizing  by  alternating  e.m.f.'s.  which  differ  in  phase  by  a 
quarter  of  a  cycle;  i.  e.,  90  degrees.  (Fig.  18.) 

TWO-WIRE  MAINS.  A  name  for  the  mains  employed  in  the 
ordinary  system  of  multiple  distribution,  as  distinguished  from  a 
three-wire  main,  or  that  used  in  a  three-wire  system. 

V. 

VECTOR  DIAGRAM.  A  diagram  representing  the  relations  of 
vector  quantities. 

VECTOR  QUANTITY.  A  quantity  possessing  both  direction 
and  magnitude. 

VECTOR  SUM.  The  geometrical  sum  of  two  or  more  vector 
quantities.  Thus,  in  Fig.  16  by  completing  the  parallelogram  formed 


FIG.  18. — Relation  of  the  Waves  of  Current,  or  e.m.f's.,  in  a  Two-phase  System. 


by  the  vectors  coLI  and  RI,  and  drawing  the  diagonal,  the  vector 
E  is  obtained,  which  is  the  vector  sum  of  wLI  and  RI.  In  practice, 
these  vectors  are  drawn  free-hand  and  the  resultants  calculated  by 
means  of  the  geometrical  laws.  (Fig.  19.) 

Example.     It  is  intended  to  find  the  value  of  e.m.f.  between  two 

E 
wires,  across  each  of  which  to  the  neutral  is  maintained  an  e.m.f.  -^r. 

It  is  known  that  these  two  e.m.f.'s.  differ  90  degrees.     In  Fig.  19, 

[53] 


Sec.  1 


DICTIONARY 


which  is  a  right  angle  triangle,  OB  =  v/OA2+AB2  or 


E 


VOLT.  The  practical  unit  of  electromotive  force.  Such  an 
electromotive  force  as  is  induced  in  a  conductor  which  cuts  lines  of 
magnetic  flux  at  the  rate  of  100,000,000  per  second.  Such  an 
electromotive  force  as  would  cause  a  current  of  one  ampere  to  flow 
against  a  resistance  of  one  ohm.  Such  an  electromotive  force  as 


B 


FIG.  19.  —  Vector  Diagram  fpr  Calculating  the  Vector  Sum  of  Two  e.m.f.'s. 
in  Ninety-degree  Phase  Relation. 


would  charge  a  condenser  of  the  capacity  of  one  farad  with  a  quantity 
of  electricity  equal  to  one  coulomb.  108  absolute  electro-magnetic 
units  of  electromotive  force. 

The  value  of  the  volt  as  adopted  by  the  International  Electrical 
Congress  of  1893,  at  Chicago,  is  an  electromotive  force  which  is 

1000 
represented  with  sufficient  accuracy  for  practical  use  by  ?7o7  of  the 

electromotive  force  between  the  poles  or  electrodes  of  the  voltaic 
cell  known  as  Clark's  cell,  at  a  temperature  of  15°  Cent,  when  pre- 
pared in  accordance  with  certain  specifications. 

VOLT  AMPERE.     The  product  of  one  volt  times  one  ampere. 

[54] 


DICTIONARY  Sec.  1 

W. 

w-hr.  An  abbreviation  for  watt-hour,  a  practical  unit  of  electric 
energy. 

WATT.  A  unit  of  electric  power.  A  volt  ampere  at  unity  power- 
factor.  The  power  developed  when  44.25  foot-pounds  of  work  are 
done  in  a  minute,  or  0.7375  foot-pound  of  work  is  done  in  a  second. 

The  value  of  the  watt  as  adopted  by  the  International  Electrical 
Congress  of  1893,  at  Chicago,  is  a  value  equal  to  107  units  of  activity 
in  the  C.G.S.  system,  and  equal  to  the  work  done  at  the  rate  of  one 
joule-per-second. 

WATT-HOUR.  A  unit  of  electric  work.  A  term  employed  to 
indicate  the  expenditure  of  an  electric  power  of  one  watt  for  an  hour. 

WATTLESS  COMPONENT  OF  CURRENT.  In  an  alternating- 
current  circuit,  that  component  of  the  current  which  is  in  quadrature 
with  the  impressed  e.m.f.  and  which,  therefore,  takes  from  or  gives 
no  energy  to  the  circuit.  In  an  alternating-current  circuit  the 
product  of  the  e.m.f.  and  the  effective  susceptance. 

WATTLESS  COMPONENT  OF  ELECTROMOTIVE  FORCE. 

In  an  alternating-current  circuit,  that  component  of  the  e.m.f.  which 
is  in  quadrature  with  the  current  strength,  and,  therefore  does  not 
work  on  the  current.  In  an  alternating-current  circuit  the  product 
of  the  current  and  the  effective  reactance. 

WAVE,  ELECTRIC.    An  electric  periodic  disturbance. 

WEATHER-PROOF  INSULATION.  A  trade-name  for  a  charac- 
ter of  insulation  consisting  of  one  or  more  layers  of  braided  material 
soaked  in  an  insulating  compound. 

WEATHER-PROOF  WIRE.  A  wire  provided  with  weather- 
proof insulation. 

WIRE.     A  slender  rod  or  filament  of  drawn  metal. 

WORK.  When  a  force  acts  on  a  body  the  product  of  the  force 
by  the  distance  through  which  it  acts  in  the  direction  of  the  force  is 
called  the  work  performed  by  the  force.  Thus,  when  a  force  applied 
to  a  heavy  body  raises  it  a  certain  vertical  distance,  work  is  per- 
formed by  the  force,  the  amount  of  the  work  being  the  product  of 
the  force  and  the  distance  of  ascent;  and  when  a  horizontal  force 
draws  a  body  horizontally  the  work  is  the  product  of  the  force  and 
the  horizontal  distance.  The  unit  of  work  is  the  work  done  by  the 
unit  force  in  acting  through  unit  distance.  When  the  dyne  is  taken 
as  unit  of  force  and  the  cm.  as  unit  of  length,  the  unit  of  work  is  that 
performed  by  a  dyne  acting  through  a  cm.  and  is  called  an  erg.  Since 
this  is  a  very  small  unit,  a  multiple  of  it,  namely  10,000,000  ergs,  is 
frequently  used  and  is  called  a  joule. 

In  practical  mechanical  work  the  unit  of  time  is  always  one 
minute,  and  the  unit  which  measures  the  work  performed  in  a  given 

[55] 


Sec.  1  DICTIONARY 

time  is  the  foot-pound  per  minute.  This  unit  is  called  the  unit  of 
mechanical  power. 

Power  is,  therefore,  rate  of  doing  work,  and  hence  the  power 
exerted  can  always  be  determined  by  dividing  the  work  done  in 
foot-pounds  by  the  time  in  minutes  required  to  do  it.  In  practical 
electrical  work  the  unit  of  time  is  the  second,  and  the  unit  which 
measures  the  work  performed  in  a  given  time  is  the  joule  per  second. 
This  unit  is  called  the  unit  of  electrical  power,  and  has  been  named 
the  watt. 

The  equation  or  formula  expressing  the  power  exerted  in  any 
electrical  circuit  is  determined  as  follows:  The  electrical  power  is 
expressed  by  watts  =  joules  per  second,  but  joules  =  volt-coulombs, 
and  hence  joules  per  second  =  volt-coulombs  per  second.  There- 
fore also,  watts  =  volt-coulombs  per  second.  Now,  coulombs  per 
second  =  amperes.  Inserting  this  value  above,  watts  =  volts  X  am- 
peres, or  W  =  EI. 

When  the  power  is  to  be  expressed  by  the  current  and  resistance, 
the  formula  is  obtained  as  follows:  According  to  formula  W=EI. 
According  to  Ohm's  law,  E=IR.  Substituting  this  value  of  E=IR 
in  the  formula  W=EI,  we  have 


When  the  power  is  to  be  expressed  by  the  electromotive  force  and 
resistance,  the  formula  is  obtained  as  follows:     According  to  formula 

E 
W  =EI.     According  to  Ohm's  law,  I  =  ~>~  .  Substituting  this  value 


E' 


R 

For  alternating  current 


Y. 

Y-CONNECTOR.  A  connector  resembling  the  letter  Y  in  shape 
for  joining  a  conductor  to  two  branch  wires. 

Y-CURRENT.  The  current  between  any  wire  of  a  three-phase 
system  and  the  neutral  point. 

z. 

ZINC,  Zn.  Atomic  weight  65.  Specific  gravity  7.14.  Melts  at 
780°  F.  Volatilizes  and  burns  in  the  air  when  melted,  with  bluish- 
white  fumes  of  zinc  oxide.  It  is  ductile  and  malleable  but  to  a 
much  less  extent  than  copper,  and  its  tenacity,  about  5000  to  6000 

[56] 


DICTIONARY 


Sec.  1 


Ibs.  per  square  inch,  is  about  one-tenth  that  of  wrought  iron. 
It  is  practically  non-corrosive  in  the  atmosphere,  a  thin  film  of  car- 
bonate of  zinc  forming  upon  it.  Cubical  expansion  between  32°  and 
212°  F.,  0.0088.  Specific  heat  .096.  Electric  conductivity  29,  heat 
conductivity  36,  silver  being  100.  Its  principal  uses  are  for  coat- 
ing iron  surfaces,  called  "galvanizing,"  and  for  making  brass  and 
other  alloys. 

ZINC  PLATING.     Electro-plating  with  zinc.     Galvanizing. 


THE  GREEK  ALPHABET. 


Name 

Large 

Small 

Commonly  used  to  designate 

alpha  .  . 

A 

a 

angles,  coefficients. 

beta  .  .  . 

B 

ft 

angles,  coefficients. 

gamma 
delta  .  . 

r 

A 

7 
8 

specific  gravity, 
density,  variation. 

epsilon  . 

E 

€ 

base  of  hyperbolic  logarithms. 

zeta  .  .  . 

Z 

r 

co-ordinates,  coefficients. 

eta  

H 

i? 

hysteresis  (Steinmetz)  coefficient,  efficiency 

theta  .  . 

e 

0 

angular  phase  displacement. 

iota  .  .  . 

I 

i 

kappa  . 

K 

K 

dielectric  constant. 

lambda 

A 

\ 

conductivity. 

mu  .... 

M 

M 

permeability. 

mi  .... 

N 

V 

reluctivity. 

xi  

H 

t 

output  coefficient. 

omicron 

O 

o 

pi  .  . 

n 

7T 

circ  jmf  erence  -T-  diameter. 

*1L 

rho  .... 

p 

P 

resistivity. 

sigma.  . 

2 

(T 

(cap.),  summation;  leakage  coefficient. 

tau  .... 

T 

T 

time-phase  displacement. 

upsilon 

T 

V 

..  ••• 

phi  .... 

<*> 

<t> 

flux. 

chi  .  .  .  . 

X 

X 

psi  

* 

* 

angular  velocity  in  time. 

omega  . 

12 

CO 

(small),  angular  velocity  in  space. 

[57] 


TABLE  No.  1 


COMMON  LOGARITHMS  OF  NUMBERS 


Sec.  1 


COMMON  LOGARITHMS 


COMMON  LOGARITHMS 

OF  NUMBERS. 

100-129 

N 

0 

• 

2 

3 

4 

5 

6 

7 

8 

9 

D 

100 

00000 

043 

087 

130 

173 

217 

260 

303 

346 

389 

43 

101 

432 

475 

518 

561 

604 

647 

689 

732 

775 

817 

43 

102 

86 

0 

903 

945 

988 

*o 

30 

*072 

*115 

*157 

* 

L99 

*242 

42 

103 

01284 

326 

368 

410 

452 

494 

536 

578 

620 

662 

42 

104 

70 

3 

745 

787 

828 

8 

70 

912 

953 

995 

* 

336 

*078 

42 

105 

02119 

160 

202 

243 

284 

325 

366 

407 

449 

490 

41 

106 

531 

572 

612 

653 

694 

735 

776 

816 

857 

898 

41 

107 

93 

8 

979 

*019 

*050 

*1 

00 

*141 

*181 

*222 

* 

252 

*302 

40 

108 

03342 

383 

423 

463 

503 

543 

583 

623 

663 

703 

40 

109 

743 

782 

822 

8S2 

902 

941 

981 

*021 

*060 

*100 

40 

110 

04139 

179 

218 

258 

297 

336 

376 

415 

454 

493 

39 

111 

532 

571 

610 

650 

689 

727 

766 

805 

844 

883 

39 

112 

92 

2 

961 

999 

*038 

*c 

77 

*11S 

*154 

*192 

* 

231 

*269 

39 

113 

05308 

346 

385 

423 

461 

500 

538 

576 

614 

652 

38 

114 

69 

0 

729 

767 

805 

a 

43 

881 

918 

956 

934 

*032 

38 

115 

06070 

108 

145 

183 

221 

258 

296 

333 

371 

408 

38 

116 

446 

483 

521 

558 

595 

633 

670 

707 

744 

781 

37 

117 

81 

9 

856 

893 

930 

9 

67 

*004 

*041 

*078 

* 

115 

*151 

37 

118 

07188 

225 

262 

298 

335 

372 

408 

445 

482 

518 

37 

119 

555 

591 

628 

664 

700 

737 

773 

809 

846 

882 

36 

120 

918 

954 

990 

*027 

*063 

*099 

*135 

*171 

*207 

*243 

36 

121 

08279 

314 

350 

386 

422 

458 

493 

529 

585 

600 

36 

122 

636 

672 

707 

743 

778 

814 

849 

884 

920 

955 

35 

123 

99 

1 

*026 

*061 

*096 

*1 

32 

*16-! 

*202 

*237 

* 

272 

*307 

35 

124 

09342 

377 

412 

447 

482 

517 

552 

587 

621 

656 

35 

125 

691 

726 

760 

795 

830 

864 

899 

934 

968 

*003 

35 

126 

10037 

072 

106 

140 

175 

209 

243 

278 

312 

346 

34 

127 

38 

0 

415 

449 

483 

5 

17 

551 

585 

619 

553 

687 

34 

128 

721 

755 

789 

823 

857 

890 

924 

958 

992 

*025 

34 

129 

11059 

093 

126 

160 

193 

227 

261 

294 

327 

361 

34 

PP 

44 

43 

42 

41 

40 

39 

38 

37 

3G 

j 

4.4 

4.3 

4.2 

4.1 

4.0 

3.9 

3.8 

3.7 

3.6 

2 

8.8 

8.6 

8.4 

8.2 

8.0 

7.8 

7.6 

7.4 

7.2 

3 

13.2 

12.9 

12.6 

12.3 

12.0 

11.7 

11.4 

11.1 

10.8 

4 

17.6 

17.2 

16.8 

16.4 

16.0 

15.6 

15.2 

14.8 

14.4 

5 

22.0 

21.5 

21.0 

20.5 

20.0 

19.5 

19.0 

18.5 

18.0 

6 

26.4 

25.8 

25.2 

24.6 

24.0 

23.4 

22.8 

22.2 

21.6 

7 

30.8 

30.1 

29.4 

28.7 

28.0 

27.3 

26.6 

25.9 

25.2 

8 

35.2 

34.4 

33.6 

32.8 

32.0 

31.2 

30.4 

29.6 

28.8 

9 

39.6 

38.7 

37.8 

36.9 

36.0 

35.1 

34.2 

33.3 

32.4 

f  60] 


COMMON  LOGARITHMS 


Sec.  1 


COMMON  LOGARITHMS  OF  NUMBERS. 

130-159 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

130 

11394 

428 

461 

494 

528 

561 

594 

628 

661 

694 

33 

131 

727 

760 

793 

826 

860 

893 

926 

959 

992 

*024 

33 

132 

12057 

090 

123 

156 

189 

222 

254 

287 

320 

352 

33 

133 

38! 

418 

450 

483 

51 

6 

548 

581 

613 

6 

46 

678 

33 

134 

710 

743 

775 

808 

840 

872 

905 

937 

969 

*001 

32 

135 

13033 

066 

098 

130 

162 

194 

226 

258 

290 

322 

32 

136 

354 

386 

418 

450 

481 

513 

545 

577 

609 

640 

32 

137 

672 

704 

735 

767 

799 

830 

862 

893 

925 

956 

32 

138 

981 

I 

*019 

*051 

*082 

*11 

4 

*145 

*176 

*208 

*2 

39 

*270 

31 

139 

14301 

333 

364 

395 

426 

457 

489 

520 

551 

582 

31 

140 

613 

644 

675 

706 

737 

768 

799 

829 

860 

891 

31 

141 

922 

953 

983 

*014 

*045 

*076 

*106 

*137 

*168 

*198 

31 

142 

15229 

259 

290 

320 

351 

381 

412 

442 

473 

503 

31 

143 

tn 

1 

564 

594 

625 

65 

5 

685 

715 

746 

1 

76 

806 

30 

144 

836 

866 

897 

927 

957 

987 

*017 

*047 

*077 

*107 

30 

145 

16137 

167 

197 

227 

256 

286 

316 

346 

3 

76 

406 

30 

146 

435 

465 

495 

524 

554 

584 

613 

643 

673 

702 

30 

147 

732 

761 

791 

820 

850 

879 

909 

938 

967 

997 

29 

148 

1702( 

056 

085 

114 

14 

3 

173 

202 

231 

2 

60 

289 

29 

149 

319 

348 

377 

406 

435 

464 

493 

522 

551 

580 

29 

150 

609 

638 

667 

696 

725 

754 

782 

811 

840 

869 

29 

151 

898 

926 

955 

984 

*013 

*041 

*070 

*099 

*127 

*156 

29 

152 

18184 

213 

241 

270 

298 

327 

355 

384 

412 

441 

29 

153 

46« 

) 

498 

526 

554 

58 

3 

611 

639 

667 

C 

96 

724 

28 

154 

752 

780 

808 

837 

865 

893 

921 

949 

977 

*005 

28 

155 

19033 

061 

089 

117 

145 

173 

201 

229 

257 

285 

28 

156 

312 

340 

368 

396 

424 

451 

479 

507 

535 

562 

28 

157 

590 

618 

645 

673 

700 

728 

756 

783 

811 

838 

28 

158 

86( 

5 

893 

921 

948 

91 

6 

*003 

*030 

*058 

*( 

85 

*112 

27 

159 

20140 

167 

194 

222 

249 

276 

303 

330 

358 

385 

27 

PP 

35 

34 

33             32 

31 

30 

29 

28 

27 

1 

3.5 

3.4 

3.3           3.2 

3.1 

3.0 

2.9 

2.8 

2.7 

2 

7.0 

6.8 

6.6            6.4 

6.2 

6.0 

5.8 

5.6 

5.4 

3 

10.5 

10.2 

9.9           9.6 

9.3 

9.0 

8.7 

8.4 

8.1 

4 

14.0 

13.6 

13.2          12.8 

12.4 

12.0 

11.6 

11.2 

10.8 

5 

17.5 

17.0 

16.5          16.0 

15.5 

15.0 

14.5 

14.0 

13.5 

6 

21.0 

29.4 

19.8          19.2 

18.6 

18.0 

17.4 

16.8 

162 

7 

24.5 

23.8 

23.1          22.4 

21.7 

21.0 

20.3 

19.6 

18.9 

8 

28.0 

27.2 

25.4          25.6 

21.8 

24.0 

23.2 

22.4 

216 

9 

31.5 

3D.6 

23.7          23.8 

27.9 

27.0 

26.1 

25.2 

24.3 

[61] 


Sec.  1 


COMMON  LOGARITHMS 


COMMON  LOGARITHMS  OF  NUMBERS. 

160-189 

N' 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

160 

20412 

439 

466 

493 

520 

548 

575 

602 

629 

656 

27 

161 

683 

710 

737 

763 

790 

817 

844 

871 

898 

925 

27 

162 

952 

978 

*005 

*032 

*059 

*085 

*112 

*139 

*165 

*192 

27 

163 

21219 

245 

272 

299 

325 

352 

378 

405 

431 

458 

27 

164 

484 

5 

LI 

537 

J 

>S4 

590 

617 

643 

669 

696 

722 

26 

165 

748 

775 

801 

827 

854 

880 

906 

932 

953 

985 

26 

166 

22011 

037 

063 

089 

115 

141 

167 

194 

220 

246 

26 

167 

272 

2 

)8 

324 

: 

(50 

376 

401 

427 

453 

479 

505 

26 

168 

531 

557 

583 

608 

634 

660 

686 

712 

737 

763 

26 

169 

789 

814 

840 

866 

891 

917 

943 

968 

994 

*019 

26 

170 

23045 

070 

096 

121 

147 

172 

198 

223 

249 

274 

25 

171 

300 

325 

350 

376 

401 

426 

452 

477 

502 

528 

25 

172 

553 

5 

16 

603 

( 

29 

654 

679 

704 

729 

754 

779 

25 

173 

805 

830 

855 

i 

80 

905 

930 

955 

980 

*005 

*030 

25 

174 

24  055 

02 

JO 

105 

3 

30 

155 

180 

204 

229 

254 

279 

25 

175 

304 

329 

353 

378 

403 

428 

452 

477 

502 

527 

25 

176 

551 

576 

601 

625 

650 

674 

699 

724 

748 

773 

25 

177 

797 

82 

2 

846 

I 

71 

895 

920 

944 

969 

993 

*018 

25 

178 

25042 

066 

091 

115 

139 

164 

188 

212 

237 

261 

24 

179 

285 

310 

334 

358 

382 

406 

431 

455 

479 

503 

24 

180 

527 

551 

575 

600 

624 

648 

672 

696 

720 

744 

24 

181 

768 

792 

816 

840 

864 

888 

912 

925 

959 

983 

24 

182 

26007 

031 

055 

079 

102 

126 

150 

174 

198 

221 

24 

183 

245 

269 

293 

316 

340 

364 

387 

411 

435 

458 

24 

184 

482 

5C 

5 

529 

5 

53 

576 

600 

623 

647 

670 

694 

24 

185 

717 

741 

764 

788 

811 

834 

858 

881 

905 

928 

23 

186 

951 

975 

998 

*021 

*045 

*088 

*091 

*114 

*138 

*161 

23 

187 

27  184 

207 

231 

254 

277 

300 

323 

346 

370 

393 

23 

188 

416 

439 

462 

485 

508 

531 

554 

577 

600 

623 

23 

189 

646 

669 

692 

715 

738 

761 

784 

807 

830 

852 

23 

PP 

27 

26 

25        24 

23 

22 

1 

2.7 

2.6 

2.5       2.4 

2.3 

2.2 

2 

5.4 

5.2 

50       4.8 

4.6 

4.4 

3 

8.1 

7.8 

7.5       7.2 

6.9 

6.6 

4 

10.8 

10.4 

10.0       9.6 

9.2 

8.8 

5 

13.5 

13.0 

12.5       12.0 

11.5 

11.0 

6 

16.2 

15.6 

15.0       14.4 

13.8 

13.2 

7 

18.9 

18.2 

17.5       16.8 

16.1 

15.4 

8 

21.6 

20.8 

20.0       19.2 

18.4 

17.6 

9 

24.3 

23.4 

22.5       21.6 

20.7 

19.8 

[62] 


COMMON  LOGARITHMS 


Sec.  1 


COMMON  LOGARITHMS  OF  NUMBERS. 

190-229 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

190 

875 

898 

921 

944 

967 

989 

*012 

*035 

*058 

*081 

23 

191 

28103 

126 

149 

171 

194 

217 

240 

262 

285 

307 

23 

192 

3*0 

353 

375 

398 

421 

443 

466 

488 

511 

533 

23 

193 

556 

578 

601 

623 

.  646 

6*8 

691 

713 

735 

758 

22 

194 

780 

803 

825 

847 

870 

892 

914 

937 

959 

981 

22 

195 

29003 

026 

048 

070 

092 

115 

137 

159 

181 

203 

22 

196 

226 

248 

270 

292 

314 

336 

358 

380 

403 

425 

22 

197 

447 

469 

491 

513 

535 

557 

579 

601 

623 

645 

22 

198 

667 

688 

710 

732 

754 

776 

798 

820 

842 

863 

22 

199 

885 

907 

929 

951 

973 

994 

*016 

*035 

*060 

*081 

22 

200 

30103 

125 

146 

168 

190 

211 

233 

255 

276 

298 

22 

201 

320 

341 

363 

384 

406 

428 

449 

471 

492 

514 

22 

202 

535 

557 

578 

600 

621 

643 

664 

685 

707 

728 

21 

203 

750 

771 

792 

814 

835 

856 

878 

899 

920 

942 

21 

204 

963 

984 

*006 

*027 

*048 

*069 

*091 

*112 

*133 

*154 

21 

205 

31175 

197 

218 

239 

260 

281 

302 

323 

345 

366 

21 

206 

387 

408 

429 

450 

471 

492 

513 

534 

555 

576 

21 

207 

597 

618 

639 

660 

681 

702 

723 

744 

765 

785 

21 

208 

806 

827 

848 

869 

890 

911 

931 

952 

973 

994 

21 

209 

32015 

035 

056 

077 

098 

118 

139 

160 

181 

201 

21 

210 

222 

243 

263 

284 

305 

325 

346 

366 

387 

408 

21 

211 

428 

449 

469 

490 

510 

531 

552 

572 

593 

613 

20 

212 

634 

654 

675 

695 

715 

736 

756 

777 

797 

818 

20 

213 

838 

858 

879 

899 

919 

940 

960 

980 

*001 

*021 

20 

214 

33041 

062 

082 

102 

122 

143 

163 

183 

203 

224 

20 

215 

244 

264 

284 

304 

325 

345 

365 

385 

405 

425 

20 

216 

445 

465 

486 

506 

526 

546 

566 

586 

606 

626 

20 

217 

646 

666 

686 

706 

726 

746 

766 

786 

806 

826 

20 

218 

846 

866 

885 

905 

925 

945 

965 

985 

*005 

*025 

20 

219 

34044 

064 

084 

104 

124 

143 

163 

183 

203 

223 

20 

220 

242 

262 

282 

301 

321 

341 

361 

380 

400 

420 

20 

221 

439 

459 

479 

498 

518 

537 

557 

577 

596 

616 

19 

222 

635 

655 

674 

694 

713 

733 

753 

772 

792 

811 

19 

223 

830 

850 

869 

889 

908 

928 

947 

967 

986 

*005 

19 

224 

35025 

044 

064 

083 

102 

122 

141 

160 

180 

199 

19 

225 

218 

238 

257 

276 

295 

315 

334 

353 

372 

392 

19 

226 

411 

430 

449 

468 

488 

507 

526 

545 

564 

583 

19 

227 

603 

622 

641 

660 

679 

698 

717 

736 

755 

774 

19 

228 

793 

813 

832 

851 

870 

889 

908 

927 

946 

965 

19 

229 

984 

*003 

*021 

*040 

*059 

*078 

*097 

*116 

*135 

*154 

19 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[  63] 


Sec.  1 


COMMON  LOGARITHMS 


COMMON  LOGARITHMS  OF  NUMBERS. 

230-269 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

230 

36173 

192 

211 

229 

248 

267 

286 

305 

324 

342 

19 

231 

361 

380 

399 

418 

436 

455 

474 

493 

511 

530 

19 

232 

549 

568 

5X6 

605 

624 

642 

661 

680 

698 

717 

19 

233 

736 

754 

773 

791 

810 

829 

847 

866 

884 

903 

19 

234 

922 

940 

959 

977 

996 

*014 

*033 

*051 

*070 

*088 

18 

235 

37107 

125 

144 

162 

181 

199 

218 

236 

254 

273 

18 

236 

291 

310 

328 

346 

365 

383 

401 

420 

438 

457 

18 

237 

475 

493 

511 

530 

548 

566 

585 

603 

621 

639 

18 

238 

658 

676 

694 

712 

731 

749 

767 

785 

803 

822 

18 

239 

840 

858 

876 

894 

912 

931 

949 

967 

985 

*003 

18 

240 

38021 

039 

057 

075 

093 

112 

130 

148 

166 

184 

18 

241 

202 

220 

238 

256 

274 

292 

310 

328 

346 

364 

18 

242 

3*2 

399 

417 

435 

453 

471 

489 

507 

525 

543 

18 

243 

561 

578 

596 

614 

632 

650 

668 

686 

703 

721 

18 

244 

739 

757 

775 

792 

810 

828 

846 

863 

881 

899 

18 

245 

917 

934 

952 

970 

987 

*005 

*023 

*041 

*058 

*076 

18 

246 

39094 

111 

129 

146 

164 

182 

199 

217 

235 

252 

18 

247 

270 

287 

305 

322 

340 

358 

375 

393 

410 

428 

18 

248 

445 

463 

480 

498 

515 

533 

550 

568 

585 

602 

18 

249 

620 

637 

655 

672 

690 

707 

724 

742 

759 

777 

17 

250 

794 

811 

829 

846 

863 

881 

898 

915 

933 

950 

17 

251 

967 

985 

*002 

*019 

*037 

*054 

*071 

*088 

*106 

*123 

17 

252 

40140 

157 

175 

192 

209 

226 

243 

261 

278 

295 

17 

253 

312 

329 

346 

364 

381 

398 

415 

432 

449 

466 

17 

254 

483 

500 

518 

535 

552 

569 

586 

603 

620 

637 

17 

255 

654 

671 

688 

705 

722 

739 

756 

773 

790 

807 

17 

256 

824 

841 

858 

875 

892 

909 

926 

943 

960 

976 

17 

257 

993 

*010 

*027 

*044 

*061 

*078 

*095 

*111 

*128 

*145 

17 

258 

41162 

179 

196 

212 

229 

246 

263 

280 

296 

313 

17 

259 

330 

347 

363 

380 

397 

414 

430 

447 

464 

481 

17 

260 

497 

514 

531 

547 

564 

581 

597 

614 

631 

647 

17 

261 

664 

681 

697 

714 

731 

747 

764 

780 

797 

814 

17 

262 

830 

847 

863 

880 

896 

913 

929 

946 

963 

979 

16 

263 

996 

*012 

*029 

*045 

*062 

*078 

*095 

*111 

*127 

*144 

16 

264 

42160 

177 

193 

210 

226 

243 

259 

275 

292 

308 

16 

265 

325 

341 

357 

374 

390 

406 

423 

439 

455 

472 

16 

266 

488 

504 

521 

537 

553 

570 

586 

602 

619 

635 

16 

267 

651 

667 

684 

700 

716 

732 

749 

765 

781 

797 

16 

268 

813 

830 

846 

862 

878 

894 

911 

927 

943 

959 

16 

269 

975 

991 

*008 

*024 

*040 

*056 

*072 

*088 

*104 

*120 

16 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[  64] 


COMMON  LOGARITHMS 


Sec.  1 


COMMON  LOGARITHMS  OF  NUMBERS. 

270-309 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

270 

43136 

152 

169 

185 

201 

217 

233 

249 

265 

281 

16 

271 

297 

313 

329 

345 

361 

377 

393 

409 

425 

441 

16 

272 

457 

473 

489 

505 

521 

537 

553 

569 

584 

600 

16 

273 

616 

632 

648 

664 

680 

696 

712 

727 

743 

759 

16 

274 

775 

791 

807 

823 

838 

854 

870 

886 

902 

917 

16 

275 

933 

949 

965 

981 

996 

*012 

*028 

*044 

*059 

*075 

16 

276 

44091 

107 

122 

138 

154 

170 

185 

201 

217 

232 

16 

277 

248 

264 

279 

295 

311 

326 

342 

358 

373 

389 

16 

278 

404 

420 

436 

451 

467 

483 

498 

514 

529 

545 

16 

279 

560 

576 

592 

607 

623 

638 

654 

669 

685 

700 

16 

280 

716 

731 

747 

762 

778 

793 

809 

824 

840 

855 

15 

281 

871 

886 

902 

917 

932 

948 

963 

979 

994 

*010 

15 

282 

45025 

040 

056 

071 

086 

102 

117 

133 

148 

163 

15 

283 

179 

194 

209 

225 

240 

255 

271 

286 

301 

317 

15 

284 

332 

347 

362 

278 

393 

408 

423 

439 

454 

469 

15 

285 

484 

500 

515 

530 

545 

561 

576 

591 

606 

621 

15 

286 

637 

652 

667 

682 

697 

712 

728 

743 

758 

773 

15 

287 

788 

803 

818 

834 

849 

864 

879 

894 

909 

924 

15 

288 

939 

954 

969 

984 

*000 

*015 

*030 

*045 

*060 

*075 

15 

289 

46090 

105 

120 

135 

150 

165 

180 

195 

210 

225 

15 

290 

240 

255 

270 

285 

300 

315 

330 

345 

359 

374 

15 

291 

389 

404 

419 

434 

449 

464 

479 

494 

509 

523 

15 

292 

538 

553 

568 

5R3 

598 

613 

627 

642 

657 

672 

15 

293 

687 

702 

716 

731 

746 

761 

776 

790 

805 

820 

15 

294 

835 

850 

864 

879 

894 

909 

923 

938 

953 

967 

15 

295 

982 

997 

*012 

*026 

*041 

*056 

*070 

*085 

*100 

*114 

15 

296 

47129 

144 

159 

173 

188 

202 

217 

232 

246 

261 

15 

297 

276 

290 

305 

319 

334 

349 

363 

378 

392 

407 

15 

298 

422 

436 

451 

465 

480 

494 

509 

524 

538 

553 

15 

299 

567 

582 

596 

611 

625 

640 

654 

669 

683 

698 

15 

300 

712 

727 

741 

756 

770 

784 

799 

813 

828 

842 

14 

301 

857 

871 

885 

900 

914 

929 

943 

958 

'  972 

986 

14 

302 

48001 

015 

029 

044 

058 

073 

087 

101 

116 

130 

14 

303 

144 

159 

173 

187 

202 

216 

230 

244 

259 

273 

14 

304 

287 

302 

316 

330 

344 

359 

373 

287 

401 

416 

14 

305 

430 

444 

458 

473 

487 

501 

515 

530 

544 

558 

14 

306 

572 

586 

601 

615 

629 

643 

657 

671 

686 

700 

14 

307 

714 

728 

742 

756 

770 

785 

799 

813 

827 

841 

14 

308 

855 

869 

883 

897 

911 

926 

940 

954 

968 

982 

14 

309 

996 

*010 

*024 

*038 

*052 

*066 

*080 

*094 

*108 

*122 

14 

N 

O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[  65  ] 


Sec.  1 


COMMON  LOGARITHMS 


COMMON  LOGARITHMS  OF  NUMBERS. 

310-349 

N 

O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

310 

49136 

150 

164 

178 

192 

206 

220 

234 

248 

262 

14 

311 

276 

290 

304 

318 

332 

346 

360 

374 

388 

402 

14 

312 

415 

429 

443 

457 

471 

485 

499 

513 

527 

541 

14 

313 

554 

568 

582 

596 

610 

624 

638 

651 

665 

679 

14 

314 

693 

707 

721 

734 

748 

762 

776 

790 

803 

817 

14 

315 

831 

845 

859 

872 

886 

900 

914 

927 

941 

955 

14 

316 

969 

982 

996 

*010 

*024 

*037 

*051 

*065 

*079 

*092 

14 

317 

50106 

120 

133 

147 

161 

174 

188 

202 

215 

229 

14 

318 

243 

256 

270 

284 

297 

311 

325 

338 

352 

365 

14 

319 

379 

393 

406 

420 

433 

447 

461 

474 

488 

501 

14 

320 

515 

529 

542 

556 

569 

583 

•  596 

610 

623 

637 

14 

321 

651 

664 

678 

691 

705 

718 

732 

745 

759 

772 

14 

322 

786 

799 

813 

826 

840 

853 

866 

880 

893 

907 

13 

323 

920 

934 

947 

961 

974 

987 

*001 

*014 

*028 

*041 

13 

324 

51055 

068 

081 

095 

108 

121 

135 

148 

162 

175 

13 

325 

188 

202 

215 

228 

242 

255 

268 

282 

295 

308 

13 

326 

322 

335 

348 

362 

375 

388 

402 

415 

428 

441 

13 

327 

455 

468 

481 

495 

508 

521 

534 

548 

561 

574 

13 

328 

587 

601 

614 

627 

640 

654 

667 

680 

693 

706 

13 

329 

720 

733 

746 

759 

772 

786 

799 

812 

825 

838 

13 

330 

851 

865 

878 

891 

904 

917 

930 

943 

957 

970 

13 

331 

983 

996 

*009 

*022 

*035 

*048 

*061 

*075 

*088 

*101 

13 

332 

52114 

127 

140 

153 

166 

179 

192 

205 

218 

231 

13 

333 

244 

257 

270 

284 

297 

310 

323 

336 

349 

362 

13 

334 

375 

388 

401 

414 

427 

440 

453 

466 

479 

492 

13 

335 

504 

517 

530 

543 

556 

569 

582 

595 

608 

621 

13 

336 

634 

647 

660 

673 

686 

699 

711 

724 

737 

750 

13 

337 

763 

776 

789 

802 

815 

827 

840 

853 

866 

879 

13 

338 

892 

905 

917 

930 

943 

956 

969 

982 

994 

*007 

13 

339 

53020 

033 

046 

058 

071 

084 

097 

110 

122 

135 

13 

340 

148 

161 

173 

186 

199 

212 

224 

237 

250 

263 

13 

341 

275 

288 

301 

314 

326 

339 

352 

364 

377 

390 

13 

342 

403 

415 

428 

441 

453 

466 

479 

491 

504 

517 

13 

343 

529 

542 

555 

567 

580 

593 

605 

618 

631 

643 

13 

344 

656 

668 

681 

694 

706 

719 

732 

744 

757 

769 

13 

345 

782 

794 

807 

820 

832 

845 

857 

870 

882 

895 

13 

346 

908 

920 

933 

945 

958 

970 

983 

995 

*008 

*020 

13 

347 

54033 

045 

058 

070 

083 

095 

108 

120 

133 

145 

13 

348 

158 

170 

183 

195 

208 

220 

233 

245 

258 

270 

12 

349 

283 

295 

307 

320 

332 

345 

357 

370 

382 

394 

12 

N 

O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[  66  ] 


COMMON  LOGARITHMS 


Sec.  1 


COMMON  LOGARITHMS  OF  NUMBERS. 

350-389 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

350 

407 

419 

432 

444 

456 

469 

481 

494 

506 

518 

12 

351 

531 

543 

555 

568 

580 

593 

605 

617 

630 

642 

12 

352 

654 

667 

679 

691 

704 

716 

728 

741 

753 

765 

12 

353 

777 

790 

802 

814 

827 

839 

851 

864 

876 

888 

12 

354 

900 

913 

925 

937 

949 

962 

974 

986 

998 

*011 

12 

355 

55023 

035 

047 

060 

072 

084 

096 

108 

121 

133 

12 

356 

145 

157 

169 

182 

194 

206 

218 

230 

242 

255 

12 

357 

267 

279 

291 

303 

315 

328 

340 

352 

364 

376 

12 

358 

388 

400 

413 

425 

437 

449 

461 

473 

485 

497 

12 

359 

509 

522 

534 

546 

558 

570 

582 

594 

606 

618 

12 

360 

630 

642 

654 

666 

678 

691 

703 

715 

727 

739 

12 

361 

751 

763 

775 

787 

799 

811 

823 

835 

847 

859 

12 

362 

871 

883 

895 

907 

919 

931 

943 

955 

967 

979 

12 

363 

991 

*003 

*015 

*027 

*038 

*050 

*062 

*074 

*086 

*098 

12 

364 

56110 

122 

134 

146 

158 

170 

182 

194 

205 

217 

12 

365 

229 

241 

253 

265 

277 

289 

301 

312 

324 

336 

12 

366 

348 

360 

372 

384 

396 

407 

419 

431 

443 

455 

12 

367 

467 

478 

490 

502 

514 

526 

538 

549 

561 

573 

12 

368 

535 

597 

608 

620 

632 

644 

656 

667 

579 

691 

12 

369 

703 

714 

726 

738 

750 

761 

773 

785 

797 

808 

12 

370 

820 

832 

844 

855 

867 

879 

891 

902 

914 

926 

12 

371 

937 

949 

961 

972 

984 

996 

*008 

*019 

*031 

*043 

12 

372 

57054 

066 

078 

089 

101 

113 

124 

13  S 

148 

159 

12 

373 

171 

183 

194 

206 

217 

229 

241 

252 

264 

276 

12 

374 

287 

299 

310 

322 

334 

345 

357 

363 

380 

392 

12 

375 

403 

415 

426 

438 

449 

461 

473 

481 

496 

507 

12 

376 

519 

530 

542 

553 

565 

576 

588 

60) 

611 

623 

12 

377 

634 

646 

657 

669 

680 

692 

703 

715 

726 

738 

11 

378 

749 

761 

772 

784 

795 

807 

818 

830 

841 

852 

11 

379 

864 

875 

887 

898 

910 

921 

933 

944 

955 

967 

11 

380 

978 

990 

*001 

*013 

*024 

*035 

*047 

*058 

*070 

*081 

11 

381 

58092 

104 

115 

127 

138 

149 

161 

172 

'184 

195 

11 

382 

206 

218 

229 

240 

252 

263 

274 

286 

297 

309 

11 

383 

320 

331 

343 

354 

365 

377 

388 

399 

410 

422 

11 

384 

433 

444 

456 

467 

478 

490 

501 

512 

524 

535 

11 

385 

546 

557 

569 

580 

591 

602 

614 

625 

636 

647 

11 

386 

659 

670 

681 

692 

704 

715 

726 

737 

749 

760 

11 

387 

771 

782 

794 

805 

816 

827 

838 

850 

861 

872 

11 

388 

883 

894 

906 

917 

928 

939 

950 

961 

973 

984 

11 

389 

995 

*006 

*017 

*028 

*040 

*051 

*062 

*073 

*084 

*095 

11 

N 

O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[  67] 


Sec.  1 


COMMON  LOGARITHMS 


COMMON  LOGARITHMS  OF  NUMBERS. 

390-429 

N 

O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

390 

59106 

118 

129 

140 

151 

162 

173 

184 

195 

207 

11 

391 

218 

229 

240 

251 

262 

273 

284 

295 

306 

318 

11 

392 

329 

340 

351 

362 

373 

384 

395 

406 

417 

428 

11 

393 

439 

450 

461 

472 

483 

494 

506 

517 

528 

539 

11 

394 

550 

561 

572 

583 

594 

605 

616 

627 

638 

649 

11 

395 

660 

671 

682 

693 

704 

715 

726 

737 

748 

759 

11 

396 

770 

780 

791 

802 

813 

824 

835 

846 

857 

868 

11 

397 

879 

890 

901 

912 

923 

934 

945 

956 

966 

977 

11 

398 

988 

999 

*010 

*021 

*032 

*043 

*054 

*065 

*076 

*086 

11 

399 

60097 

108 

119 

130 

141 

152 

163 

173 

184 

195 

11 

400 

206 

217 

228 

239 

249 

260 

271 

282 

293 

304 

11 

401 

314 

325 

336 

347 

358 

369 

379 

390 

401 

412 

11 

402 

423 

433 

444 

455 

466 

477 

487 

498 

509 

520 

11 

403 

531 

541 

552 

563 

574 

584 

595 

606 

617 

627 

11 

404 

638 

649 

660 

670 

681 

692 

703 

713 

724 

735 

11 

405 

746 

756 

767 

778 

788 

799 

810 

821 

831 

842 

11 

406 

853 

863 

874 

885 

895 

906 

917 

927 

938 

949 

11 

407 

959 

970 

981 

991 

*002 

*013 

*023 

*034 

*045 

*055 

11 

408 

61066 

077 

087 

098 

109 

119 

130 

140 

151 

162 

11 

409 

172 

183 

194 

204 

215 

225 

236 

247 

257 

268 

11 

410 

278 

289 

300 

310 

321 

331 

342 

352 

363 

374 

11 

411 

384 

395 

405 

416 

426 

437 

448 

458 

469 

479 

11 

412 

490 

500 

511 

521 

532 

542 

553 

563 

574 

584 

11 

413 

595 

606 

616 

627 

637 

648 

658 

669 

679 

690 

11 

414 

700 

711 

721 

731 

742 

752 

763 

773 

784 

794 

10 

415 

805 

815 

826 

836 

847 

857 

868 

878 

888 

899 

10 

416 

909 

920 

930 

941 

951 

962 

972 

982 

993 

*003 

10 

417 

62014 

024 

034 

045 

055 

066 

076 

086 

097 

107 

10 

418 

118 

128 

138 

149 

159 

170 

180 

190 

201 

211 

10 

419 

221 

232 

242 

252 

263 

273 

284 

294 

304 

315 

10 

420 

325 

335 

346 

356 

366 

377 

387 

397 

408 

418 

10 

421 

428 

439 

449 

459 

469 

480 

490 

500 

511 

521 

10 

422 

531 

542 

552 

562 

572 

583 

593 

603 

613 

624 

10 

423 

634 

644 

655 

665 

675 

685 

696 

706 

716 

726 

10 

424 

737 

747 

757 

767 

778 

788 

798 

808 

818 

829 

10 

425 

839 

849 

859 

870 

880 

890 

900 

910 

921 

931 

10 

426 

941 

951 

961 

972 

982 

932 

*002 

*012 

*022 

*033 

10 

427 

63043 

052 

063 

073 

083 

094 

104 

114 

124 

134 

10 

428 

144 

155 

165 

175 

185 

195 

205 

215 

225 

236 

10 

429 

246 

256 

266 

276 

286 

296 

306 

317 

327 

337 

10 

N 

O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[  68] 


COMMON  LOGARITHMS 


Sec.  1 


COMMON  LOGARITHMS  OF  NUMBERS. 

430-469 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8  . 

9 

D 

430 

347 

357 

367 

377 

387 

397 

407 

417 

428 

438 

10 

431 

448 

458 

468 

478 

488 

498 

508 

518 

528 

538 

10 

432 

548 

558 

568 

579 

589 

599 

609 

619 

629 

639 

10 

433 

649 

659 

669 

679 

689 

699 

709 

719 

729 

739 

10 

434 

749 

759 

769 

779 

789 

799 

809 

819 

829 

839 

10 

435 

849 

859 

869 

879 

889 

899 

9Q9 

919 

929 

939 

10 

436 

949 

959 

969 

979 

988 

998 

*008 

*018 

*028 

*038 

10 

437 

64048 

058 

068 

078 

088 

098 

108 

118 

128 

137 

10 

438 

147 

157 

167 

177 

187 

197 

207 

217 

227 

237 

10 

439 

246 

256 

266 

276 

286 

296 

306 

316 

326 

335 

10 

440 

345 

355 

365 

275 

285 

395 

404 

414 

424 

434 

10 

441 

444 

454 

464 

473 

483 

493 

503 

513 

523 

532 

10 

442 

542 

552 

562 

572 

582 

591 

601 

611 

621 

631 

10 

443 

640 

650 

660 

670 

680 

689 

699 

709 

719 

729 

10 

444 

738 

748 

758 

768 

777 

787 

797 

807 

816 

826 

10 

445 

836 

846 

855 

865 

875 

885 

895 

904 

914 

924 

10 

446 

933 

943 

953 

963 

972 

982 

992 

*002 

*011 

*021 

10 

447 

65031 

040 

050 

060 

070 

079 

089 

099 

108 

118 

10 

448 

128 

137 

147 

157 

167 

176 

186 

196 

205 

215 

10 

449 

225 

234 

244 

254 

263 

273 

283 

292 

302 

312 

10 

450 

321 

331 

341 

350 

360 

369 

379 

389 

398 

408 

10 

451 

418 

427 

437 

447 

456 

466 

475 

485 

495 

504 

10 

452 

514 

523 

533 

543 

552 

562 

571 

581 

591 

600 

10 

453 

610 

619 

629 

639 

648 

658 

667 

677 

686 

696 

10 

454 

706 

715 

725 

734 

744 

753 

763 

772 

782 

792 

9 

455 

801 

811 

820 

830 

839 

849 

858 

868 

877 

887 

9 

456 

896 

906 

916 

925 

935 

944 

954 

963 

973 

982 

9 

457 

992 

*001 

*011 

*020 

*030 

*039 

*049 

*058 

*068 

*077 

9 

458 

66087 

096 

106 

115 

124 

134 

143 

153 

162 

172 

9 

459 

181 

191 

200 

210 

219 

229 

238 

247 

257 

266 

9 

460 

276 

285 

295 

304 

314 

323 

332 

342 

351 

361 

9 

461 

370 

380 

389 

398 

408 

417 

427 

436 

445 

455 

9 

'  462 

464 

474 

483 

492 

502 

511 

521 

530 

539 

549 

9 

463 

558 

567 

577 

586 

596 

605 

614 

624 

633 

642 

9 

464 

652 

661 

671 

680 

689 

699 

708 

717 

727 

736 

9 

465 

745 

755 

764 

773 

783 

792 

801 

811 

820 

829 

9 

466 

839 

848 

857 

867 

876 

885 

894 

904 

913 

922 

9 

467 

932 

941 

950 

960 

969 

978 

987 

997 

*006 

*015 

9 

468 

67025 

034 

043 

052 

062 

071 

080 

089 

099 

108 

9 

469 

117 

127 

136 

145 

154 

164 

173 

182 

191 

201 

9 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[  69] 


Sec.  1 


COMMON  LOGARITHMS 


COMMON  LOGARITHMS  OF  NUMBERS. 

470-509 

N 

0 

i 

2 

3 

4 

5 

6 

7 

8 

9 

D 

470 

210 

219 

228 

237 

247 

256 

265 

274 

284 

293 

9 

471 

302 

311 

321 

330 

339 

348 

357 

367 

376 

385 

9 

472 

394 

403 

413 

422 

431 

440 

449 

459 

468 

477 

9 

473 

486 

495 

504 

514 

523 

532 

541 

550 

560 

569 

9 

474 

578 

587 

596 

605 

614 

624 

633 

642 

651 

660 

9 

475 

669 

679 

688 

697 

706 

715 

724 

733 

742 

752 

9 

476 

761 

770 

779 

788 

797 

806 

815 

825 

834 

843 

9 

477 

852 

861 

870 

879 

888 

897 

906 

916 

925 

934 

9 

478 

943 

952 

961 

970 

979 

988 

997 

*006 

*015 

*024 

9 

479 

68034 

043 

052 

061 

070 

079 

088 

097 

106 

115 

9 

480 

124 

133 

142 

151 

160 

169 

178 

187 

196 

205 

9 

481 

215 

224 

233 

242 

251 

260 

269 

278 

287 

296 

9 

482 

305 

314 

323 

332 

341 

350 

359 

368 

377 

386 

9 

483 

395 

404 

413 

422 

431 

440 

449 

458 

467 

476 

9 

484 

485 

494 

502 

511 

520 

529 

538 

547 

556 

565 

9 

485 

574 

583 

592 

601 

610 

619 

628 

637 

646 

655 

9 

486 

664 

673 

681 

690 

699 

708 

717 

726 

735 

744 

9 

487 

753 

762 

771 

780 

789 

797 

806 

815 

824 

833 

9 

488 

842 

851 

860 

869 

878 

886 

895 

904 

913 

922 

9 

489 

931 

940 

949 

958 

966 

975 

984 

993 

*002 

*011 

9 

490 

69020 

028 

037 

046 

055 

064 

073 

082 

090 

099 

9 

491 

108 

117 

126 

135 

144 

152 

161 

170 

179 

188 

492 

197 

205 

214 

223 

232 

241 

249 

258 

267 

276 

493 

285 

294 

302 

311 

320 

329 

338 

346 

355 

364 

494 

373 

381 

390 

399 

408 

417 

425 

434 

443 

452 

495 

461 

469 

478 

487 

496 

504 

513 

522 

531 

539 

496 

548 

557 

566 

574 

583 

592 

601 

609 

618 

627 

497 

636 

644 

653 

662 

671 

679 

688 

697 

705 

714 

498 

723 

732 

740 

749 

758 

767 

775 

784 

793 

801 

9 

499 

810 

819 

827 

836 

845 

854 

862 

871 

880 

888 

9 

500 

897 

906 

914 

923 

932 

940 

949 

958 

966 

975 

9 

501 

984 

992 

*001 

*010 

*018 

*027 

*036 

*044 

*053 

*062 

9 

502 

70070 

079 

088 

096 

105 

114 

122 

131 

140 

148 

9 

503 

157 

165 

174 

183 

191 

200 

209 

217 

226 

234 

9 

504 

243 

252 

260 

269 

278 

286 

295 

303 

312 

321 

9 

505 

329 

338 

346 

355 

364 

372 

381 

389 

398 

406 

9 

506 

415 

424 

432 

441 

449 

458 

467 

475 

484 

492 

9 

507 

501 

509 

518 

526 

535 

544 

552 

561 

5*9 

578 

9 

508 

586 

595 

603 

612 

621 

629 

638 

646 

655 

663 

9 

509 

672 

680 

689 

697 

706 

714 

723 

731 

740 

749 

9 

N 

o 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[  70  ] 


COMMON  LOGARITHMS 


Sec.  1 


COMMON  LOGARITHMS  OF  NUMBERS. 

510-549 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

510 

757 

766 

774 

783 

791 

800 

808 

817 

825 

834 

9 

511 

842 

851 

859 

868 

876 

885 

893 

902 

910 

919 

9 

512 

927 

935 

944 

952 

961 

969 

978 

986 

995 

*003 

9 

513 

71012 

020 

029 

037 

046 

054 

063 

071 

079 

088 

8 

514 

096 

105 

113 

122 

130 

139 

147 

155 

164 

172 

8 

515 

181 

189 

198 

206 

214 

223 

231 

240 

248 

257 

8 

516 

265 

273 

282 

290 

299 

307 

315 

324 

332 

341 

8 

517 

349 

357 

366 

374 

383 

391 

399 

408 

416 

425 

8 

518 

433 

441 

450 

458 

466 

475 

483 

492 

500 

508 

8 

519 

517 

525 

533 

542 

550 

559 

567 

575 

584 

592 

8 

520 

600 

609 

617 

625 

634 

642 

650 

659 

667 

675 

8 

521 

684 

692 

700 

709 

717 

725 

734 

742 

750 

759 

8 

522 

767 

775 

784 

792 

800 

809 

817 

825 

834 

842 

8 

523 

850 

858 

867 

875 

883 

892 

900 

908 

917 

925 

8 

524 

933 

941 

950 

958 

966 

975 

983 

991 

999 

*008 

8 

525 

72016 

024 

032 

041 

049 

057 

066 

074 

082 

090 

8 

526 

099 

107 

115 

123 

132 

140 

148 

156 

165 

173 

8 

527 

181 

189 

198 

206 

214 

222 

230 

239 

247 

255 

8 

528 

263 

272 

280 

288 

296 

304 

313 

321 

329 

337 

8 

529 

346 

354 

362 

370 

378 

387 

395 

403 

411 

419 

8 

530 

428 

436 

444 

452 

460 

469 

477 

485 

493 

501 

8 

531 

509 

518 

526 

534 

542 

550 

558 

567 

575 

583 

8 

532 

591 

599 

607 

616 

624 

632 

640 

648 

656 

665 

8 

533 

673 

681 

689 

697 

705 

713 

722 

730 

738 

746 

8 

534 

754 

762 

770 

779 

787 

795 

803 

811 

819 

827 

8 

535 

835 

843 

852 

860 

868 

876 

884 

892 

900 

908 

8 

536 

916 

925 

933 

941 

949 

957 

965 

973 

981 

989 

8 

537 

997 

*006 

*014 

*022 

*030 

*038 

*046 

*054 

*062 

*070 

8 

538 

73078 

086 

094 

102 

111 

119 

127 

135 

143 

151 

8 

539 

159 

167 

175 

183 

191 

199 

207 

215 

223 

231 

8 

540 

239 

247 

255 

263 

272 

280 

288 

296 

304 

312 

8 

541 

320 

328 

336 

344 

352 

360 

368 

376 

384 

392 

8 

542 

400 

408 

416 

424 

432 

440 

448 

456 

464 

472 

8 

543 

480 

488 

496 

504 

512 

520 

528 

536 

544 

552 

8 

544 

560 

568 

576 

584 

592 

600 

608 

616 

624 

632 

8 

545 

640 

648 

656 

664 

672 

679 

687 

695 

703 

711 

8 

546 

719 

727 

735 

743 

751 

759 

767 

775 

783 

791 

8 

547 

799 

807 

815 

823 

830 

838 

846 

854 

862 

870 

8 

548 

878 

886 

894 

902 

910 

918 

926 

933 

941 

949 

8 

549 

957 

965 

973 

981 

989 

997 

*OQ5 

*013 

*020 

*028 

8 

N 

O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

I  71  ] 


Sec.  1 


COMMON  LOGARITHMS 


COMMON  LOGARITHMS  OF  NUMBERS. 

550-589 

N 

0 

i 

2 

3 

4 

5 

6 

7 

8 

9 

D 

550 

74036 

044 

052 

060 

068 

076 

084 

092 

099 

107 

8 

551 

115 

123 

131 

139 

147 

155 

162 

170 

178 

186 

8 

552 

194 

202 

210 

218 

225 

223 

241 

249 

257 

265 

8 

553 

273 

280 

288 

296 

304 

312 

320 

327 

335 

343 

8 

554 

351 

359 

367 

374 

382 

390 

398 

406 

414 

421 

8 

555 

429 

437 

445 

453 

461 

468 

476 

484 

492 

500 

8 

556 

507 

515 

523 

531 

539 

547 

554 

562 

570 

578 

8 

557 

5*6 

593 

601 

609 

617 

624 

632 

640 

648 

656 

8 

558 

6*3 

671 

679 

687 

695 

702 

710 

718 

726 

733 

8 

559 

741 

749 

757 

764 

772 

780 

788 

796 

803 

811 

8 

560 

819 

827 

834 

842 

850 

858 

865 

873 

881 

889 

8 

561 

896 

904 

912 

920 

927 

935 

943 

950 

958 

966 

8 

562 

974 

981 

989 

997 

*095 

*012 

*020 

*028 

*035 

*043 

8 

563 

75051 

059 

066 

074 

082 

089 

097 

105 

113 

120 

8 

564 

128 

136 

143 

151 

159 

166 

174 

182 

189 

197 

8 

565 

205 

213 

220 

228 

236 

243 

251 

259 

266 

274 

8 

566 

282 

289 

297 

305 

312 

320 

328 

335 

343 

351 

8 

567 

358 

366 

374 

381 

389 

397 

404 

312 

420 

427 

8 

568 

435 

442 

450 

458 

465 

473 

481 

488 

496 

504 

8 

569 

511 

519 

526 

534 

542 

549 

557 

565 

572 

580 

8 

570 

587 

595 

603 

610 

618 

626 

633 

641 

648 

656 

8 

571 

664 

671 

679 

686 

694 

702 

709 

717 

724 

732 

8 

572 

740 

747 

755 

762 

770 

778 

785 

793 

800 

808 

8 

573 

815 

823 

831 

838 

846 

853 

8S1 

868 

876 

884 

8 

574 

891 

899 

906 

914 

921 

929 

937 

944 

952 

959 

8 

575 

967 

974 

982 

989 

997 

*005 

*012 

*020 

*027 

*035 

8 

576 

76042 

050 

057 

065 

072 

080 

087 

095 

103 

110 

8 

577 

118 

125 

133 

140 

148 

155 

163 

170 

178 

185 

8 

578 

193 

200 

208 

215 

223 

230 

238 

245 

253 

260 

8 

579 

268 

275 

283 

290 

298 

305 

313 

320 

328 

335 

8 

580 

343 

350 

358 

365 

373 

380 

388 

395 

403 

410 

8 

581 

418 

425 

433 

440 

448 

455 

462 

470 

477 

485 

7 

582 

492 

500 

507 

515 

522 

530 

537 

545 

552 

559 

7 

583 

567 

574 

582 

589 

597 

604 

612 

619 

626 

634 

7 

5«4 

641 

649 

658 

664 

671 

678 

686 

693 

701 

708 

7 

585 

716 

723 

730 

738 

745 

753 

760 

768 

775 

782 

7 

586 

790 

797 

805 

812 

819 

827 

834 

842 

849 

856 

7 

587 

864 

871 

879 

886 

893 

901 

908 

916 

923 

930 

7 

588 

938 

945 

953 

960 

967 

975 

982 

989 

997 

*004 

7 

589 

77012 

019 

026 

034 

041 

048 

056 

063 

070 

078 

7 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[  72  ] 


COMMON  LOGARITHMS 


Sec.  1 


COMMON  LOGARITHMS  OF  NUMBERS. 

590-629 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

590 

085 

093 

100 

107 

115 

122 

129 

137 

144 

151 

7 

591 

159 

166 

173 

181 

188 

195 

203 

210 

217 

225 

7 

592 

232 

240 

247 

254 

262 

269 

276 

283 

291 

298 

7 

593 

305 

313 

320 

327 

335 

342 

349 

357 

364 

371 

7 

594 

379 

386 

393 

401 

408 

415 

422 

430 

437 

444 

7 

595 

452 

459 

466 

474 

481 

488 

495 

503 

510 

517 

7 

596 

525 

532 

539 

546 

554 

561 

568 

576 

583 

590 

7 

597 

597 

605 

612 

619 

627 

634 

641 

648 

656 

663 

7 

598 

670 

677 

685 

692 

699 

706 

714 

721 

728 

735 

7 

599 

743 

750 

757 

764 

772 

779 

786 

793 

801 

808 

7 

600 

815 

822 

830 

837 

844 

851 

859 

866 

873 

880 

7 

601 

887 

895 

902 

909 

916 

924 

931 

938 

945 

952 

7 

602 

960 

967 

974 

981 

988 

996 

*003 

*010 

*017 

*025 

7 

603 

78032 

039 

046 

053 

061 

068 

075 

082 

089 

097 

7 

604 

104 

111 

118 

125 

132 

140 

147 

154 

161 

168 

605 

176 

183 

190 

197 

204 

211 

219 

226 

233 

240 

606 

247 

254 

262 

269 

276 

283 

290 

297 

305 

312 

607 

319 

326 

333 

340 

347 

355 

362 

369 

376 

383 

608 

390 

398 

405 

412 

419 

426 

433 

440 

447 

455 

609 

462 

469 

476 

483 

490 

497 

504 

512 

519 

526 

610 

533 

540 

547 

554 

561 

569 

576 

583 

590 

597 

7 

611 

604 

611 

618 

625 

633 

640 

647 

654 

661 

668 

7 

612 

675 

682 

689 

696 

704 

711 

718 

725 

732 

739 

7 

613 

746 

753 

760 

767 

774 

781 

789 

796 

803 

810 

7 

614 

817 

824 

831 

838 

845 

852 

859 

866 

873 

880 

7 

615 

888 

895 

902 

909 

916 

923 

930 

937 

944 

951 

7 

616 

958 

965 

972 

979 

986 

993 

*000 

*007 

*C14 

*021 

7 

617 

79029 

036 

043 

050 

057 

064 

071 

078 

085 

092 

7 

618 

099 

106 

113 

120 

127 

134 

141 

148 

155 

162 

7 

619 

169 

176 

183 

190 

197 

204 

211 

218 

225 

232 

7 

620 

239 

246 

253 

260 

267 

274 

281 

288 

295 

302 

7 

621 

309 

316 

323 

330 

337 

344 

351 

358 

365 

372 

7 

622 

379 

386 

393 

400 

407 

414 

421 

428 

435 

442 

7 

623 

449 

456 

463 

470 

477 

484 

491 

498 

505 

511 

7 

6?4 

518 

525 

532 

539 

546 

553 

560 

567 

574 

581 

7 

625 

588 

595 

602 

609 

616 

623 

630 

637 

644 

650 

7 

626 

657 

664 

671 

678 

685 

692 

699 

706 

713 

720 

7 

627 

727 

734 

741 

748 

754 

761 

768 

775 

782 

789 

7 

628 

796 

803 

810 

817 

824 

831 

837 

844 

851 

858 

7 

629 

865 

872 

879 

886 

893 

900 

906 

913 

920 

927 

7 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[73] 


Sec.  1 


COMMON  LOGARITHMS 


COMMON  LOGARITHMS  OF  NUMBERS. 

630-669 

N 

O 

1  - 

2 

3 

4 

5 

6 

7 

8 

9 

D 

630 

934 

941 

948 

955 

962 

969 

975 

982 

989 

996 

7 

631 

80003 

010 

017 

024 

030 

037 

044 

051 

058 

065 

7 

632 

072 

079 

085 

092 

099 

106 

113 

120 

127 

134 

7 

633 

140 

147 

154 

161 

168 

175 

182 

188 

195 

202 

7 

634 

209 

216 

223 

229 

236 

243 

250 

257 

264 

271 

7 

635 

277 

284 

291 

298 

305 

312 

318 

325 

332 

339 

7 

636 

346 

353 

359 

366 

373 

380 

387 

393 

400 

407 

7 

637 

414 

421 

428 

434 

441 

448 

455 

462 

468 

475 

7 

638 

482 

489 

496 

502 

509 

516 

523 

530 

536 

543 

7 

639 

550 

557 

564 

570 

577 

584 

591 

598 

604 

611 

7 

640 

618 

625 

632 

638 

645 

652 

659 

665 

672 

679 

7 

641 

686 

693 

699 

706 

713 

720 

726 

733 

740 

747 

7 

642 

754 

760 

767 

774 

781 

787 

794 

801 

808 

814 

7 

643 

821 

828 

835 

841 

848 

855 

862 

868 

875 

882 

7 

644 

889 

895 

902 

909 

916 

922 

929 

936 

943 

949 

7 

645 

956 

963 

969 

976 

983 

990 

996 

*003 

*010 

*017 

7 

646 

81023 

030 

037 

043 

050 

057 

064 

070 

077 

084 

7 

647 

090 

097 

104 

111 

117 

124 

131 

137 

144 

151 

7 

648 

158 

164 

171 

178 

184 

191 

198 

204 

211 

218 

7 

649 

224 

231 

238 

245 

251 

258 

265 

271 

278 

285 

7 

650 

291 

298 

305 

311 

318 

325 

331 

338 

345 

351 

7 

651 

358 

365 

371 

378 

385 

391 

398 

405 

411 

418 

7 

652 

425 

431 

438 

445 

451 

458 

465 

471 

478 

485 

7 

653 

491 

498 

505 

511 

518 

525 

531 

538 

544 

551 

7 

654 

558 

564 

571 

578 

584- 

591 

598 

604 

611 

617 

7 

655 

624 

631 

637 

644 

651 

657 

664 

671 

677 

684 

7 

656 

690 

697 

704 

710 

717 

723 

730 

T37 

743 

750 

7 

657 

757 

763 

770 

776 

783 

790 

796 

803 

809 

816 

7 

658 

823 

829 

836 

842 

849 

856 

862 

869 

875 

882 

7 

659 

889 

895 

902 

908 

915 

921 

928 

935 

941 

948 

7 

660 

954 

961 

968 

974 

981 

987 

994 

*000 

*007 

*014 

7 

661 

82020 

027 

033 

040 

046 

053 

060 

066 

073 

079 

7 

662 

086 

092 

099 

105 

112 

119 

125 

132 

138 

145 

7 

663 

151 

158 

164 

171 

178 

184 

191 

197 

204 

210 

7 

664 

217 

223 

230 

236 

243 

249 

256 

263 

269 

276 

7 

665 

282 

289 

295 

302 

308 

315 

321 

328 

334 

341 

7 

666 

347 

354 

360 

367 

373 

380 

387 

393 

400 

406 

7 

667 

413 

419 

426 

432 

439 

445 

452 

458 

465 

471 

7 

668 

478 

484 

491 

497 

504 

510 

517 

523 

530 

536 

7 

669 

543 

549 

556 

562 

569 

575 

582 

588 

595 

601 

7 

N 

O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[74] 


COMMON  LOGARITHMS 


Sec.  1 


COMMON  LOGARITHMS  OF  NUMBERS. 

670-709 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

670 

607 

614 

620 

627 

633 

640 

646 

653 

659 

666 

7 

671 
672 

672 
737 

679 

743 

685 
750 

692 
756 

698 

763 

705 
769 

711 
776 

718 
782 

at 

730 

795 

6 
6 

673 

802 

808 

814 

821 

827 

834 

840 

847 

853 

860 

6 

674 

866 

872 

879 

885 

892 

898 

905 

911 

918 

924 

6 

675 

930 

937 

943 

950 

956 

963 

969 

975 

982 

988 

6 

676 

995 

*001 

*008 

*014 

*020 

*027 

*033 

*040 

*046 

*052 

6 

677 

83059 

065 

072 

078 

085 

091 

097 

104 

110 

117 

6 

678 

123 

129 

136 

142 

149 

155 

161 

168 

174 

181 

6 

679. 

187 

193 

200 

206 

213 

219 

225 

232 

238 

245 

6 

680 

251 

257 

264 

270 

276 

283 

289 

296 

302 

308 

6 

681 

315 

321 

327 

334 

340 

347 

353 

359 

366 

372 

6 

682 

378 

385 

391 

398 

404 

410 

417 

423 

429 

436 

6 

683 

442 

448 

455 

461 

467 

474 

480 

487 

493 

499 

6 

684 

506 

512 

518 

525 

531 

537 

544 

550 

556 

563 

6 

685 

569 

575 

582 

588 

594 

601 

607 

613 

620 

626 

6 

686 

632 

639 

645 

651 

658 

664 

670 

677 

683 

689 

6 

687 

696 

702 

708 

715 

721 

727 

734 

740 

746 

753 

6 

688 

759 

765 

771 

778 

784 

790 

797 

803 

809 

816 

6 

689 

822 

823 

835 

841 

847 

853 

860 

866 

872 

879 

6 

690 

885 

891 

897 

904 

910 

916 

923 

929 

935 

942 

6 

691 

948 

954 

960 

967 

973 

979 

985 

992 

998 

*004 

6 

692 

84011 

017 

023 

029 

036 

042 

048 

055 

061 

067 

6 

693 

073 

080 

086 

092 

098 

105 

111 

117 

123 

130 

6 

694 

136 

142 

148 

155 

161 

167 

173 

180 

186 

192 

6 

695 

198 

205 

211 

217 

223 

230 

236 

242 

248 

255 

6 

696 

261 

267 

273 

280 

286 

292 

298 

305 

311 

317 

6 

697 

323 

330 

336 

342 

348 

354 

361 

367 

373 

379 

6 

698 

386 

392 

398 

404 

410 

417 

423 

429 

435 

442 

6 

699 

448 

454 

460 

466 

473 

479 

485 

491 

497 

504 

6 

700 

510 

516 

522 

528 

535 

541 

547 

553 

559 

566 

6 

701 

572 

578 

584 

590 

597 

603 

609 

615 

621 

628 

702 

634 

640 

646 

652 

658 

665 

671 

677 

683 

689 

703 

696 

702 

708 

714 

720 

726 

733 

739 

745 

751 

704 

757 

763 

770 

776 

782 

788 

794 

800 

807 

813 

705 

819 

825 

831 

837 

844 

850 

856 

862 

868 

874 

706 

880 

887 

893 

899 

905 

911 

917 

924 

930 

936 

6 

707 

942 

948 

954 

960 

967 

973 

979 

985 

991 

997 

6 

708 

85003 

009 

016 

022 

028 

034 

040 

046 

052 

058 

6 

709 

065 

071 

077 

083 

089 

095 

101 

107 

114 

120 

6 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[75] 


Sec.  1 


COMMON  LOGARITHMS 


COMMON  LOGARITHMS  OF  NUMBERS. 

710-749 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

710 

126 

132 

138 

144 

150 

156 

163 

169 

175 

181 

6 

711 

187 

193 

199 

205 

211 

217 

224 

230 

236 

242 

6 

712 

248 

254 

260 

266 

272 

278 

285 

291 

297 

303 

6 

713 

309 

315 

321 

327 

333 

339 

345 

352 

358 

364 

6 

714 

370 

376 

382 

388 

394 

400 

406 

412 

418 

425 

6 

715 

431 

437 

443 

449 

455 

461 

467 

473 

479 

485 

6 

716 

491 

497 

503 

509 

516 

522 

528 

534 

540 

546 

6 

717 

552 

558 

564 

570 

576 

582 

588 

594 

600 

606 

6 

718 

612 

618 

625 

631 

637 

643 

649 

655 

661 

667 

6 

719 

673 

679 

685 

691 

697 

703 

709 

715 

721 

727 

6 

720 

733 

739 

745 

751 

757 

763 

769 

775 

781 

788 

6 

721 

794 

800 

806 

812 

818 

824 

830 

836 

842 

848 

6 

722 

854 

860 

866 

872 

878 

884 

890 

896 

902 

908 

6 

723 

914 

920 

926 

932 

938 

944 

950 

956 

962 

968 

6 

724 

974 

980 

986 

992 

998 

*004 

*010 

*016 

*022 

*028 

6 

725 

86034 

040 

046 

052 

058 

064 

070 

076 

082 

088 

6 

726 

094 

100 

106 

112 

118 

124 

130 

136 

141 

147 

6 

727 

153 

159 

165 

171 

177 

183 

189 

195 

201 

207 

6 

728 

213 

219 

225 

231 

237 

243 

249 

255 

261 

267 

6 

729 

273 

279 

285 

291 

297 

303 

308 

314 

320 

326 

6 

730 

332 

338 

344 

350 

356 

362 

368 

374 

380 

386 

6 

731 

392 

398 

404 

410 

415 

421 

427 

433 

439 

445 

6 

732 

451 

457 

463 

469 

475 

481 

487 

493 

499 

504 

733 

510 

516 

522 

528 

534 

540 

546 

552 

558 

564 

6 

734 

570 

576 

581 

587 

593 

599 

605 

611 

617 

623 

6 

735 

629 

635 

641 

646 

652 

658 

664 

670 

676 

682 

6 

736 

688 

694 

700 

705 

711 

717 

723 

729 

735 

741 

737 

747 

753 

759 

764 

770 

776 

782 

788 

794 

800 

738 

806 

812 

817 

823 

829 

835 

841 

847 

853 

859 

739 

864 

870 

876 

882 

888 

894 

900 

906 

911 

917 

740 

923 

929 

935 

941 

947 

953 

958 

964 

970 

976 

741 

982 

938 

994 

999 

*005 

*011 

*017 

*023 

*029 

*035 

742 

87040 

046 

052 

058 

064 

070 

075 

081 

087 

093 

743 

099 

105 

111 

116 

122 

128 

134 

140 

146 

151 

744 

157 

163 

169 

175 

181 

186 

192 

198 

204 

210 

745 

216 

221 

227 

233 

239 

245 

251 

256 

262 

268 

746' 

274 

280 

286 

291 

297 

303 

309 

315 

320 

326 

747 

332 

338 

344 

349 

355 

361 

367 

373 

379 

384 

748 

390 

396 

402 

408 

413 

419 

425 

431 

437 

442 

749 

448 

454 

460 

466 

471 

477 

483 

489 

495 

500 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[76] 


COMMON  LOGARITHMS 


Sec.  1 


COMMON  LOGARITHMS  OF  NUMBERS. 

750-789 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

750 

506 

512 

518 

523 

529 

535 

541 

547 

552 

558 

6 

751 

564 

570 

576 

581 

587 

593 

599 

604 

610 

616 

6 

752 

622 

628 

633 

639 

645 

651 

656 

662 

668 

674 

6 

753 

679 

685 

691 

697 

703 

708 

714 

720 

726 

731 

6 

754 

737 

743 

749 

754 

760 

766 

772 

777 

783 

789 

6 

755 

795 

800 

806 

812 

818 

823 

829 

835 

841 

846 

6 

756 

852 

858 

864 

869 

875 

881 

887 

892 

898 

904 

6 

757 

910 

915 

921 

927 

933 

938 

944 

950 

955 

961 

6 

758 

967 

973 

978 

984 

990 

996 

*001 

*007 

*013 

*018 

6 

759 

88024 

030 

036 

041 

047 

053 

058 

064 

070 

076 

6 

760 

081 

087 

093 

098 

104 

110 

116 

121 

127 

133 

6 

761 

138 

144 

150 

156 

161 

167 

173 

178 

184 

190 

6 

762 

195 

201 

207 

213 

218 

224 

230 

235 

241 

247 

6 

763 

252 

258 

264 

270 

275 

281 

287 

292 

298 

304 

6 

764 

309 

315 

321 

326 

332 

338 

343 

349 

355 

360 

6 

765 

366 

372 

377 

383 

389 

395 

400 

406 

412 

417 

6 

766 

423 

429 

434 

440 

446 

451 

457 

463 

468 

474 

6 

767 

480 

485 

491 

497 

502 

508 

513 

519 

525 

530 

6 

768 

536 

542 

547 

553 

559 

564 

570 

576 

581 

587 

6 

769 

593 

598 

604 

610 

615 

621 

627 

632 

638 

643 

6 

770 

649 

655 

660 

666 

672 

677 

683 

689 

694 

700 

6 

771 

705 

711 

717 

722 

728 

734 

739 

745 

750 

756 

6 

772 

762 

767 

773 

779 

784 

790 

795 

801 

807 

812 

6 

773 

818 

824 

829 

835 

840 

846 

852 

857 

863 

868 

6 

774 

874 

880 

885 

891 

897 

902 

908 

913 

919 

925 

6 

775 

930 

936 

041 

947 

953 

958 

964 

969 

975 

981 

6 

776 

986 

992 

997 

*003 

*009 

*014 

*020 

*025 

*031 

*037 

6 

777 

89042 

048 

053 

059 

064 

070 

076 

081 

087 

092 

6 

778 

098 

104 

109 

115 

120 

126 

131 

137 

143 

148 

6 

779 

154 

159 

165 

170 

176 

182 

187 

193 

198 

204 

6 

780 

209 

215 

221 

226 

232 

237 

243 

248 

254 

260 

6 

781 

265 

271 

276 

282 

287 

293 

298 

304 

310 

315 

6 

782 

321 

326 

332 

337 

343 

348 

354 

350 

365 

371 

6 

783 

376 

382 

387 

393 

398 

404 

409 

415 

421 

426 

6 

784 

432 

437 

443 

448 

454 

459 

465 

470 

476 

481 

6 

785 

487 

492 

498 

504 

509 

515 

520 

526 

531 

537 

6 

786 

542 

548 

553 

559 

564 

570 

575 

581 

586 

592 

6 

787 

597 

603 

609 

614 

620 

625 

631 

636 

642 

647 

6 

788 

653 

658 

664 

669 

675 

680 

686 

691 

697 

702 

6 

789 

708 

713 

719 

724 

730 

735 

741 

746 

752 

757 

6 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[77] 


Sec.  1 


COMMON  LOGARITHMS 


COMMON  LOGARITHMS  OF  NUMBERS. 

790-829 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

790 

763 

768 

774 

779 

785 

790 

796 

801 

807 

812 

5 

791 

818 

823 

829 

834 

840 

845 

851 

856 

862 

867 

5 

792 

873 

878 

883 

889 

894 

900 

905 

911 

916 

922 

5 

793 

927 

933 

938 

944 

949 

955 

960 

966 

971 

977 

5 

794 

982 

988 

993 

998 

*004 

*009 

*015 

*020 

*026 

*031 

5 

795 

90037 

042 

048 

053 

059 

064 

069 

075 

080 

086 

5 

796 

091 

097 

102 

108 

113 

119 

124 

129 

135 

140 

5 

797 

146 

151 

157 

162 

168 

173 

179 

184 

189 

195 

5 

798 

200 

206 

211 

217 

222 

227 

233 

238 

244 

249 

5 

799 

255 

260 

266 

271 

276 

282 

287 

293 

298 

304 

5 

800 

309 

314 

320 

325 

331 

336 

342 

347 

352 

358 

5 

801 

363 

369 

374 

380 

385 

390 

396 

401 

407 

412 

5 

802 

417 

423 

428 

434 

439 

445 

450 

455 

461 

466 

5 

803 

472 

477 

482 

488 

493 

499 

504 

509 

515 

520 

5 

804 

526 

531 

536 

542 

547 

553 

558 

563 

569 

574 

5 

805 

580 

585 

590 

596 

601 

607 

612 

617 

623 

628 

5 

806 

634 

639 

644 

650 

655 

660 

666 

671 

677 

682 

5 

807 

687 

693 

698 

703 

709 

714 

720 

725 

730 

736 

5 

808 

741 

747 

752 

757 

763 

768 

773 

779 

784 

789 

5 

809 

795 

800 

806 

811 

816 

822 

827 

832 

838 

843 

5 

810 

849 

854 

859 

865 

870 

875 

881 

886 

891 

897 

5 

811 

902 

907 

913 

918 

924 

929 

934 

940 

945 

950 

5 

812 

956 

961 

966 

972 

977 

982 

988 

993 

998 

*004 

5 

813 

91009 

014 

020 

025 

030 

036 

041 

046 

052 

057 

5 

814 

062 

068 

073 

078 

084 

089 

094 

100 

105 

110 

5 

815 

116 

121 

126 

132 

137 

142 

148 

153 

158 

164 

5 

816 

169 

174 

180 

185 

190 

196 

201 

206 

212 

217 

5 

817 

222 

228 

233 

238 

243 

249 

254 

259 

265 

270 

5 

818 

275 

281 

286 

291 

297 

302 

307 

312 

318 

323 

5 

819 

328 

334 

339 

344 

350 

355 

360 

365 

371 

376 

5 

820 

381 

387 

392 

397 

403 

408 

413 

418 

424 

429 

5 

821 

434 

440 

445 

450 

455 

461 

466 

471 

477 

482 

5 

822 

487 

492 

498 

503 

508 

514 

519 

524 

529 

535 

5 

823 

540 

545 

551 

556 

561 

566 

572 

577 

582 

587 

5 

824 

593 

598 

603 

609 

614 

619 

624 

630 

635 

640 

5 

825 

645 

651 

656 

661 

666 

672 

677 

682 

687 

693 

5 

826 

698 

703 

709 

714 

719 

724 

730 

735 

740 

745 

5 

827 

751 

756 

761 

766 

772 

777 

782 

787 

793 

798 

5 

828 

803 

808 

814 

819 

824 

829 

834 

840 

845 

850 

5 

829 

855 

861 

866 

871 

876 

882 

887 

892 

897 

903 

5 

N 

0 

1 

2 

3 

4 

5 

5 

7 

8 

9 

D 

[78] 


COMMON  LOGARITHMS 


Sec.  1 


COMMON  LOGARITHMS  OF  NUMBERS. 

830-869 

N 

O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

830 

908 

913 

918 

924 

929 

934 

939 

944 

950 

955 

5 

831 

960 

965 

971 

976 

981 

986 

991 

997 

*002 

*007 

5 

832 

92012 

018 

023 

028 

033 

038 

044 

049 

054 

059 

5 

833 

065 

070 

075 

080 

085 

091 

096 

101 

106 

111 

5 

834 

117 

122 

127 

132 

137 

143 

148 

153 

158 

163 

5 

835 

169 

174 

479 

184 

189 

195 

200 

205 

210 

215 

5 

836 

221 

226 

231 

236 

241 

247 

252 

257 

262 

267 

5 

837 

273 

278 

283 

288 

293 

298 

304 

309 

314 

319 

5 

838 

324 

330 

335 

340 

345 

350 

355 

361 

366 

371 

5 

839 

376 

381 

387 

392 

397 

402 

407 

412 

418 

423 

5 

840 

428 

433 

438 

443 

449 

454 

459 

464 

469 

474 

5 

841 

480 

485 

490 

495 

500 

505 

511 

516 

521 

526 

5 

842 

531 

536 

542 

547 

552 

557 

562 

567 

572 

578 

5 

843 

583 

588 

593 

598 

603 

609 

614 

619 

624 

629 

5 

844 

634 

639 

645 

650 

655 

660 

665 

670 

675 

681 

5 

845 

686 

691 

696 

701 

706 

711 

716 

722 

727 

732 

5 

846 

737 

742 

747 

752 

758 

763 

768 

773 

778 

783 

5 

847 

788 

793 

799 

804 

809 

814 

819 

824 

829 

834 

5 

848 

840 

845 

850 

855 

860 

865 

870 

875 

881 

886 

5 

849 

891 

896 

901 

906 

911 

916 

921 

927 

932 

937 

5 

850 

942 

947 

952 

957 

962 

967 

973 

978 

983 

988 

5 

851 

993 

998 

*003 

-008 

*013 

*018 

*024 

*029 

*034 

*039 

5 

852 

93044 

049 

054 

059 

064 

069 

075 

080 

085 

090 

5 

853 

095 

100 

105 

110 

115 

120 

125 

131 

136 

141 

5 

854 

146 

151 

156 

161 

166 

171 

176 

181 

186 

192 

5 

855 

197 

202 

207 

212 

217 

222 

227 

232 

237 

242 

5 

856 

247 

252 

258 

263 

268 

273 

278 

283 

288 

293 

5 

857 

298 

303 

308 

313 

318 

323 

328 

334 

339 

344 

5 

858 

349 

354 

359 

364 

369 

374 

379 

384 

389 

394 

5 

859 

399 

404 

409 

414 

420 

425 

430 

435 

440 

445 

5 

860 

450 

455 

460 

465 

470 

475 

480 

485 

490 

495 

5 

861 

500 

505 

510 

515 

520 

526 

531 

536 

541 

546 

5 

862 

551 

556 

561 

566 

571 

576 

581 

586 

591 

596 

5 

863 

601 

606 

611 

616 

621 

626 

631 

636 

641 

646 

5 

864 

651 

656 

661 

666 

671 

676 

682 

687 

692 

697 

5 

865 

702 

707 

712 

717 

722 

727 

732 

737 

742 

747 

5 

866 

752 

757 

762 

767 

772 

777 

782 

787 

792 

797 

5 

867 

802 

807 

812 

817 

822 

827 

832 

837 

842 

847 

5 

868 

852 

857 

862 

867 

872 

877 

882 

887 

892 

897 

5 

869 

902 

907 

912 

917 

922 

927 

932 

937 

942 

947 

5 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[79] 


Sec.  1 


COMMON  LOGARITHMS 


COMMON  LOGARITHMS  OF  NUMBERS. 

870-909 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

870 

952 

957 

962 

967 

972 

977 

982 

987 

992 

997 

5 

871 

94002 

007 

012 

017 

022 

027 

032 

037 

042 

047 

5 

872 

052 

057 

062 

067 

072 

077 

082 

086 

091 

096 

5 

873 

101 

106 

111 

116 

121 

126 

131 

136 

141 

146 

5 

874 

151 

15S 

161 

166 

171 

176 

181 

186 

191 

196 

5 

875 

201 

206 

211 

216 

221 

226 

231 

236 

240 

245 

5 

876 

250 

255 

260 

265 

270 

275 

280 

285 

290 

295 

5 

877 

300 

305 

310 

315 

320 

325 

330 

335 

340 

345 

5 

878 

349 

354 

359 

364 

369 

374 

379 

384 

389 

394 

5 

879 

399 

404 

409 

414 

419 

424 

429 

433 

438 

443 

5 

880 

448 

453 

458 

463 

468 

473 

478 

483 

488 

493 

881 

498 

503 

507 

512 

517 

522 

527 

532 

537 

542 

5 

882 

547 

552 

557 

562 

567 

571 

576 

581 

586 

591 

5 

883 

596 

601 

606 

611 

616 

621 

626 

630 

635 

640 

5 

884 

645 

650 

655 

660 

665 

670 

675 

680 

685 

689 

5 

885 

694 

699 

704 

709 

714 

719 

724 

729 

734 

738 

5 

886 

743 

748 

753 

758 

763 

768 

773 

778 

783 

787 

5 

887 

792 

797 

802 

807 

812 

817 

822 

827 

832 

836 

5 

888 

841 

846 

851 

856 

861 

866 

871 

876 

880 

885 

5 

889 

890 

895 

900 

905 

910 

915 

919 

924 

929 

934 

5 

890 

939 

944 

949 

954 

959 

963 

968 

973 

978 

983 

5 

891 

988 

993 

998 

*002 

*007 

*012 

*017 

*022 

*027 

*032 

5 

892 

95036 

041 

046 

051 

056 

061 

066 

071 

075 

080 

6 

893 

085 

090 

095 

100 

105 

109 

114 

119 

124 

129 

5 

894 

134 

139 

143 

148 

153 

158 

163 

168 

173 

177 

5 

895 

182 

187 

192 

197 

202 

207 

211 

216 

221 

226 

5 

896 

231 

236 

240 

245 

250 

255 

260 

265 

270 

274 

5 

897 

279 

284' 

289 

294 

299 

303 

308 

313 

318 

323 

5 

898 

328 

332 

337 

342 

347 

352 

357 

361 

366 

371 

5 

899 

376 

381 

386 

390 

395 

400 

405 

410 

415 

419 

5 

900 

424 

429 

434 

439 

444 

448 

453 

458 

463 

468 

5 

901 

472 

477 

482 

487 

492 

497 

501 

506 

511 

516 

5 

902 

521 

525 

530 

535 

540 

545 

550 

554 

559 

564 

5 

903 

569 

574 

578 

583 

588 

593 

598 

602 

607 

612 

5 

904 

617 

622 

626 

631 

636 

641 

646 

650 

655 

660 

5 

905 

665 

670 

674 

679 

684 

689 

694 

698 

703 

708 

6 

906 

713 

718 

722 

727 

732 

737 

742 

746 

751 

756 

5 

907 

761 

766 

770 

775 

780 

785 

789 

794 

799 

804 

5 

908 

809 

813 

818 

823 

828 

832 

837 

842 

847 

852 

5 

909 

856 

861 

866 

871 

875 

880 

885 

890 

895 

899 

5 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[80] 


COMMON  LOGARITHMS 


Sec.  1 


COMMON  LOGARITHMS  OF  NUMBERS. 

910-949 

N 

0 

• 

2 

3 

4 

5 

6 

7 

& 

9 

D 

910 

904 

909 

914 

918 

923 

928 

933 

938 

942 

947 

5 

911 

952 

957 

961 

966 

971 

976 

980 

985 

990 

995 

912 

999 

*004 

*009 

*014 

*019 

*023 

*028 

*033 

*038 

*042 

913 

96047 

052 

057 

061 

066 

071 

076 

080 

085 

090 

914 

095 

099 

104 

109 

114 

118 

123 

128 

133 

137 

915 

142 

147 

152 

156 

161 

166 

171 

175 

180 

185 

916 

190 

194 

199 

204 

209 

213 

218 

223 

227 

232 

5 

917 

237 

242 

246 

251 

256 

261 

265 

270 

275 

280 

5 

918 

284 

289 

294 

298 

303 

308 

313 

317 

322 

327 

5 

919 

332 

336 

341 

346 

350 

355 

360 

365 

369 

374 

5 

920 

379 

384 

388 

393 

398 

402 

407 

412 

417 

421 

5 

921 

426 

431 

435 

440 

445 

450 

454 

459 

464 

468 

5 

922 

473 

478 

483 

487 

492 

497 

501 

506 

511 

515 

5 

923 

520 

525 

530 

534 

539 

544 

548 

553 

558 

562 

5 

924 

567 

572 

577 

581 

586 

591 

595 

600 

605 

609 

5 

925 

614 

619 

624 

628 

633 

638 

642 

647 

652 

656 

5 

926 

661 

666 

670 

675 

680 

685 

689 

694 

699 

703 

5 

927 

708 

713 

717 

722 

727 

731 

736 

741 

745 

750 

5 

928 

755 

759 

764 

769 

774 

778 

783 

788 

792 

797 

5 

929 

802 

806 

811 

816 

820 

825 

830 

834 

839 

844 

5 

930 

848 

853 

858 

862 

867 

872 

876 

881 

886 

890 

5 

931 

895 

900 

904 

909 

914 

918 

923 

928 

932 

937 

5 

932 

942 

946 

951 

956 

960 

965 

970 

974 

979 

984 

5 

933 

988 

993 

997 

*002 

*007 

*011 

*016 

*021 

*025 

*030 

5 

934 

97035 

039 

044 

049 

053 

058 

063 

067 

072 

077 

5 

935 

081 

086 

090 

095 

100 

104 

109 

114 

118 

123 

5 

936 

128 

132 

137 

142 

146 

151 

155 

160 

165 

169 

5 

937 

174 

179 

183 

188 

192 

197 

202 

206 

211 

216 

5 

938 

220 

225 

230 

234 

239 

243 

248 

253 

257 

262 

5 

939 

267 

271 

276 

280 

285 

290 

294 

299 

304 

308 

5 

940 

313 

317 

322 

327 

331 

336 

340 

345 

350 

354 

5 

941 

359 

364 

368 

373 

377 

382 

387 

391 

396 

400 

5 

942 

405 

410 

414 

419 

424 

428 

433 

437 

442 

447 

5 

943 

451 

456 

460 

465 

470 

474 

479 

483 

488 

493 

5 

944 

497 

502 

506 

511 

516 

520 

525 

529 

534 

539 

5 

945 

543 

548 

552 

557 

562 

566 

571 

575 

580 

585 

5 

946 

589 

594 

598 

603 

607 

612 

617 

621 

626 

630 

5 

947 

635 

640 

644 

649 

653 

658 

663 

667 

672 

676 

5 

948 

681 

685 

690 

695 

699 

704 

708 

713 

717 

722 

5 

949 

727 

731 

736 

740 

745 

749 

754 

759 

763 

768 

5 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[81] 


Sec.  1 


COMMON  LOGARITHMS 


COMMON  LOGARITHMS  OF  NUMBERS. 

95O-989 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

950 

772 

777 

782 

786 

791 

795 

800 

804 

809 

813 

5 

.951 

818 

823 

827 

832 

836 

841 

845 

850 

855 

859 

5 

952 

864 

868 

873 

877 

882 

886 

891 

896 

900 

905 

5 

953 

909 

914 

918 

923 

928 

932 

937 

941 

946 

950 

5 

954 

955 

959 

964 

968 

973 

978 

982 

987 

991 

996 

5 

955 

98000 

005 

009 

014 

019 

023 

028 

032 

037 

041 

5 

956 

046 

050 

055 

059 

064 

068 

073 

078 

082 

087 

5 

957 

091 

096 

100 

105 

109 

114 

118 

123 

127 

132 

5 

958 

137 

141 

146 

150 

155 

159 

164 

168 

173 

177 

5 

959 

182 

186 

191 

195 

200 

204 

209 

214 

218 

223 

5 

960 

227 

232 

236 

241 

245 

250 

254 

259 

263 

268 

5 

961 

272 

277 

281 

286 

290 

295 

299 

304 

308 

313 

5 

962 

318 

322 

327 

331 

336 

340 

345 

349 

354 

358 

5 

963 

363 

367 

372 

376 

381 

385 

390 

394 

399 

403 

5 

964 

408 

412 

417 

421 

426 

430 

435 

439 

444 

448 

5 

965 

453 

457 

462 

466 

471 

475 

480 

484 

489 

493 

4 

966 

498 

502 

507 

511 

516 

520 

525 

529 

534 

538 

4 

967 

543 

547 

552 

556 

561 

565 

570 

574 

579 

583 

4 

968 

588 

592 

597 

601 

605 

610 

614 

619 

623 

628 

4 

969 

632 

637 

641 

646 

650 

655 

659 

664 

668 

673 

4 

970 

677 

682 

686 

691 

695 

700 

704 

709 

713 

717 

4 

971 

722 

726 

731 

735 

740 

744 

749 

753 

758 

762 

4 

972 

767 

771 

776 

780 

784 

789 

793 

798 

802 

807 

4 

973 

811 

816 

820 

825 

829 

834 

838 

843 

847 

851 

4 

974 

856 

860 

865 

869 

874 

878 

883 

887 

892 

896 

4 

975 

900 

905 

909 

914 

918 

923 

927 

932 

936 

941 

4 

976 

945 

949 

954 

958 

963 

967 

972 

976 

981 

985 

4 

977 

989 

994 

998 

*003 

*007 

*012 

*016 

*021 

*025 

*029 

4 

978 

99034 

038 

043 

047 

052 

056 

061 

065 

069 

074 

4 

979 

078 

083 

087 

092 

096 

100 

105 

109 

114 

118 

4 

980 

123 

127 

131 

136 

140 

145 

149 

154 

158 

162 

4 

981 

167 

171 

176 

180 

185 

189 

193 

198 

202 

207 

4 

982 

211 

216 

220 

224 

229 

233 

238 

242 

247 

251 

4 

983 

255 

260 

264 

269 

273 

277 

282 

286 

291 

295 

4 

984 

300 

304 

308 

313 

317 

322 

326 

330 

335 

339 

4 

985 

344 

348 

352 

357 

361 

366 

370 

374 

379 

383 

4 

986 

388 

392 

396 

401 

405 

410 

414 

419 

423 

427 

4 

987 

432 

436 

441 

445 

449 

454 

458 

463 

467 

471 

4 

988 

476 

480 

484 

489 

493 

498 

502 

506 

511 

515 

4 

989  . 

520 

524 

528 

533 

537 

542 

546 

550 

555 

559 

4 

N 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

D 

[  82  ] 


COMMON  LOGARITHMS 


Sec.  1 


COMMON  LOGARITHMS  OF  NUMBERS. 
990-999 


990 

991 
992 
993 
994 
995 

996 
997 
998 
999 


564 

607 
651 
695 


870 
913 
957 


568 

612 
656 
699 
743 
787 

830 
874 
917 
961 


572 

616 
660 
704 

747 
791 

835 
878 
922 
965 


577 


621 
664 


752 
795 


839 


926 
970 


581 

625 
669 
712 
756 
800 

843 
887 
930 
974 


585 

629 
673 
717 
760 
804 

848 
891 
935 
978 


590 

634 
677 
721 
765 
808 

852 
896 
939 


594 


682 
726 
769 
813 

856 
900 
944 
987 


599 

642 
686 
730 
774 
817 

861 
904 
948 
991 


603 

647 
691 
734 
778 
822 

865 
909 
952 
996 


[83] 


TABLE  2 
NATURAL  TRIGONOMETRIC  FUNCTIONS 


Sec.  1       NATURAL  TRIGONOMETRIC  FUNCTIONS 


FOUR-PLACE  VALUES  OF  TRIGONOMETRIC 

FUNCTIONS. 

o       / 

N.  Sin. 

N.  Tan. 

N.  Cot. 

N.  Cos. 

0    00 

.0000 

.0000 

00 

1.0000 

00    90 

10 

.0029 

.0029 

343.77 

1.0000 

50 

20 

.0058 

.0058 

171.89 

1.0000 

40 

30 

.0087 

.0087 

114.59 

1.0000 

30 

40 

.0116 

.0116 

85.940 

.9999 

20 

50 

.0145 

.0145 

68.750 

.9999 

10 

1    00 

.0175 

.0175 

57.290 

.9998 

00    89 

10 

.0204 

.0204 

49.104 

.9998 

50 

20 

.0233 

.0233 

42.964 

.9997 

40 

30 

.0262 

.0262 

38.188 

.9997 

30 

40 

.0291 

.0291 

34.368 

.9996 

20 

50 

.0320 

.0320 

31.242 

.9995 

10 

2    00 

.0349 

.0349 

28.636 

.9994 

00    88 

10 

.0378 

.0378 

26.432 

.9993 

50 

20 

.0407 

.0407 

24.542 

.9992 

40 

30 

.0436 

.0437 

22.904 

.9990 

30 

40 

.0465 

.0466 

21.470 

.9989 

20 

50 

.0494 

.0495 

20.206 

.9988 

10 

3    00 

.0523 

.0524 

19.081 

.9986 

00    87 

10 

.0552 

.0553 

18.075 

.9985 

50 

20 

.0581 

.0582 

17.169 

.9983 

40 

30 

.0610 

.0612 

16.350 

.9981 

30 

40 

.0640 

.0641 

15.605 

.9980 

20 

50 

.0669 

.0670 

14.924 

.9978 

10 

4    00 

.0698 

.0699 

14.301 

.9976 

00    86 

10 

.0727 

.0729 

13.727 

.9974 

50 

20 

.0756 

.0758 

13.197 

.9971 

40 

30 

.0785 

.0787 

12.706 

.9969 

30 

40 

.0814 

.0816 

12.251 

.9967 

20 

50 

.0843 

.0846 

11.826 

.9964 

10 

5    00 

.0872 

.0875 

11.430 

.9962 

00    85 

10 

.0901    . 

.0904 

11.059 

.9959 

50 

20 

.0929 

.0934 

10.712 

.9957 

40 

30 

.0958 

.0963 

10.385 

.9954 

30 

40 

.0987 

.0992 

10.078 

.9951 

20 

50 

.1016 

.1022 

9.7882 

.9948 

10 

6    00 

.1045 

.1051 

9.5144 

.9945 

00    84 

10 

.1074 

.1080 

9.2553 

.9942 

50 

20 

.1103 

.1110 

9.0098 

.9939 

40 

30 

.1132 

.1139 

8.7769 

.9936 

30 

40 

.1161 

.1169 

8.5555 

.9932 

20 

50 

.1190 

.1198 

8.3450 

.9929 

10 

7    00 

.1219 

.1228 

8.1443 

.9925 

00    83 

10 

.1248 

.1257 

7.9530 

.9922 

50 

20 

.1276 

.1287 

7.7704 

.9918 

40 

30 

.1305 

.1317 

7.5958 

.9914 

30 

40 

.1334 

.1346 

7.4287 

.9911 

20 

50 

.1363 

.1376 

7.2687 

.9907 

10 

N.  Coa. 

N.  Cot. 

N.  Tan. 

N.  Sin. 

/       o 

[  86] 


NATURAL  TRIGONOMETRIC  FUNCTIONS      Sec.  1 


FOUR-PLACE  VALUES  OF  TRIGONOMETRIC 

FUNCTIONS. 

0          / 

N.  Sin. 

N.  Tan. 

N.  Cot. 

N.  Cos. 

8    00 

.1392 

.1405 

7.1154 

.9903 

00    82 

10 

.1421 

.1435 

6.9682 

.9899 

50 

20 

.1449 

.1465 

6.8269 

.9894 

40 

30 

.1478 

.1495 

6.6912 

.9890 

30 

40 

.1507 

.1524 

6.5606 

.9886 

20 

50 

.1536 

.1554 

6.4348 

.9881 

10 

9    00 

.1564 

.1584 

6.3138 

.9877 

00    81 

10 

.1593 

.1614 

6.1970 

.9872 

50 

20 

.1622 

.1644 

6.0844 

.9868 

40 

30 

.1650 

.1673 

5.9758 

.9863 

30 

40 

.1679 

.1703 

5.8708 

.9858 

20 

50 

.1708 

.1733 

5.7694 

.9853 

10 

10    00 

.1736 

.1763 

5.6713 

.9848 

00    80 

10 

.1765 

.1793 

5.5764 

.9843 

50 

20 

.1794 

.1823 

5.4845 

.9838 

40 

30 

.1822 

.1853 

5.3955 

.9833 

30 

40 

.1851 

.1883 

5.3093 

.9827 

20 

50 

.1880 

.1914 

5.2257 

.9822 

10 

11     00 

.1908 

.1944 

5.1446 

.9816 

00    79 

10 

.1937 

.1974 

5.0658 

.9811 

50 

20 

.1965 

.2004 

4.9894 

.9805 

40 

30 

.1994 

.2035 

4.9152 

.9799 

30 

40 

.2022 

.2065 

4.8430 

.9793 

20 

50 

.2051 

.2095 

4.7729 

.9787 

10 

12     00 

.2079 

.2126 

4.7046 

.9781 

00    78 

10 

.2108 

.2156 

4.6382 

.9775 

50 

20 

.2136 

.2186 

4.5736 

.9769 

40 

30 

.2164 

.2217 

4.5107 

.9763 

30 

40 

.2193 

.2247 

4.4494 

.9757 

20 

50 

.2221 

.2278 

4.3897 

.9750 

10 

13     00 

.2250 

.2309 

4.3315 

.9744 

00    77 

10 

.2278 

.2339 

4.2747 

.9737 

50 

20 

.2306 

.2370 

4.2193 

.9730 

40 

30 

.2334 

.2401 

4.1653 

.9724 

30 

40 

.2363 

.2432 

4.1126 

.9717 

20 

50 

.2391 

.2462 

4.0611 

.9710 

10 

14    00 

.2419 

.2493 

4.0108 

.9703 

00    76 

10 

.2447 

.2524 

3.9617 

.9696 

50 

20 

.2476 

.2555 

3.9136 

.9689 

40 

30 

.2504 

.2586 

3.8667 

.9681 

30 

40 

.2532 

.2617 

3.8208 

.9674 

20 

50 

.2560 

.2648 

3.7760 

.9667 

10 

15    00 

.2588 

.2679 

3.7321 

.9659 

00    75 

10 

.2616 

.2711 

3.6891 

.9652 

50 

20 

.2644 

.2742 

3.6470 

.9644 

40 

30 

.2672 

.2773 

3.6059 

.9636 

30 

40 

.2700 

.2805 

3.5656 

.9628 

20 

50 

.2728 

.2836 

3.5261 

.9621 

10 

N.  Cos. 

N.  Cot. 

N.  Tan. 

N.  Sin. 

>      o 

[  87  ] 


Sec.  1      NATURAL  TRIGONOMETRIC  FUNCTIONS 


FOUR-PLACE  VALUES  OF  TRIGONOMETRIC 

FUNCTIONS. 

0         / 

N.  Sin. 

N.  Tan. 

N.  Cot. 

N.  Cos. 

16    00 

.2756 

.2867 

3.4874 

.9613 

00    74 

10 

.2784 

.2899 

3.4495 

.9605 

50 

20 

.2812 

.2931 

3.4124 

.95% 

40 

30 

.2840 

.2962 

3.3759 

.9588 

30 

40 

.2868 

.2994 

3.3402 

.9580 

20 

50 

.2896 

.3026 

3.3052 

.9572 

10 

17    00 

.2924 

.3057 

3.2709 

.9563 

00    73 

10 

.2952 

.3089 

3.2371 

.9555 

50 

20 

.2979 

.3121 

3.2041 

.9546 

40 

30 

.3007 

.3153 

3.1716 

.9537 

30 

40 

.3035 

.3185 

3.1397 

.9528 

20 

50 

.3062 

.3217 

3.1084 

.9520 

10 

18    00 

.3090 

.3249 

3.0777 

.9511 

00    72 

10 

.3118 

.3281 

3.0475 

.9502 

50 

20 

.3145 

.3314 

3.0178 

.9492 

40 

30 

.3173 

.3346 

2.9887 

.9483 

30 

40 

.3201 

.3378 

2.9600 

.9474 

20 

50 

.3228 

.3411 

2.9319 

.9465 

10 

19    00 

.3256 

.3443 

2.9042 

.9455 

00    71 

10 

.3283 

.3476 

2.8770 

.9446 

50 

20 

.3311 

.3508 

2.8502 

.9436 

40 

30 

.3338 

.3541 

2.8239 

.9426 

30 

40 

.3365 

.3574 

2.7980 

.9417 

20 

50 

.3393 

.3607 

2.7725 

.9407 

10 

20    00 

.3420 

.3640 

2.7475 

.9397 

00    70 

10 

.3448 

.3673 

2.7228 

.9387 

50 

20 

.3475 

.3706 

2.6985 

.9377 

40 

30 

.3502 

.3739 

2.6746 

.9367 

30 

40 

.3529 

.3772 

2.6511 

.9356 

20 

50 

.3557 

.3805 

2.6279 

.9346 

10 

21    00 

.3584 

.3839 

2.6051 

.9336 

00    69 

10 

.3611 

.3872 

2.5826 

.9325 

50 

20 

.3638 

.3906 

2.5605 

.9315 

40 

30 

.3665 

.3939 

2.5386 

.9304 

30 

40 

.3692 

.3973 

2.5172 

.9293 

20 

50 

.3719 

.4006 

2.4960 

.9283 

10 

22     00 

.3746 

.4040 

2.4751 

.9272 

00    68 

10 

.3773 

.4074 

2.4545 

.9261 

50 

20 

.3800 

.4108 

2.4342 

.9250 

40 

30 

.3827 

.4142 

2.4142 

.9239 

30 

40 

.3854 

.4176 

2.3945 

.9228 

20 

50 

.3881 

.4210 

2.3750 

.9216 

10 

23    00 

.3907 

.4245 

2.3559 

.9205 

00    67 

10 

.3934 

.4279 

2.3369 

.9194 

50 

20 

.3961 

.4314 

2.3183 

.9182 

40 

30 

.3987 

.4348 

2.2998 

.9171 

30 

40 

.4014 

.4383 

2.2817 

.9159 

20 

50 

.4041 

.4417 

2.2637 

.9147 

10 

N.  Cos. 

N.  Cot. 

N.  Tan. 

N.  Sin. 

>       o 

[88] 


NATURAL  TRIGONOMETRIC  FUNCTIONS      Sec.  1 


FOUR-PLACE  VALUES  OF  TRIGONOMETRIC 

FUNCTIONS. 

0            / 

N.  Sin. 

N.  Tan. 

N.  Cot. 

N.  Cos. 

24    00 

.4067 

.4452 

2.2460 

.9135 

00    66 

10 

.4094 

.4487 

2.2286 

.9124 

50 

20 

.4120 

.4522 

2.2113 

.9112 

40 

30 

.4147 

.4557 

2.1943 

.9100 

30 

40 

.4173 

.4592 

2.1775 

.9088 

20 

50 

.4200 

.4628 

2.1609  . 

.9075 

10 

25    00 

.4226 

.4663 

2.1445 

.9063 

00    65 

10 

.4253 

.4699 

2.1283 

.9051 

50 

20 

.4279 

.4734 

2.1123 

.9038 

40 

30 

.4305 

.4770 

2.0965 

.9026 

30 

40 

.4331 

.4806 

2.0809 

.9013 

20 

50 

.4358 

.4841 

2.0655 

.9001 

10 

26    00 

.4384 

.4877 

2.0503 

.8988 

00    64 

10 

.4410 

.4913 

2.0353 

.8975 

50 

20 

.4436 

.4950 

2.0204 

.8962 

40 

30 

.4462 

.4986 

2.0057 

.8949 

30 

40 

.4488 

.5022 

1.9912 

.8936 

20 

50 

.4514 

.5059 

1.9768 

.8923 

10 

27    00 

.4540 

.5095 

1.9626 

.8910 

00    63 

10 

.4566 

.5132 

1.9486 

.8897 

50 

20 

.4592 

.5169 

1.9347 

.8884 

40 

30 

.4617 

.5206 

1.9210 

.8870 

30 

40 

.4643 

.5243 

1.9074 

.8857 

20 

50 

.4669 

.5280 

1.8940 

.8843 

10 

28    00 

.4695 

.5317 

1.8807 

.8829 

00    62 

10 

.4720 

.5354 

1.8676 

.8816 

50 

20 

.4746 

.5392 

1.8546 

.8802 

40 

30 

.4772 

.5430 

1.8418 

.8788 

30 

40 

.4797 

.5467 

1.8291 

.8774 

20 

50 

.4823 

.5505 

1.8165 

.8760 

10 

29    00 

.4848 

.5543 

1.8040 

.8746 

00    61 

10 

.4874 

.5581 

1.7917 

.8732 

50 

20 

.4899 

.5619 

1.7796 

.8718 

40 

30 

.4924 

.5658 

1.7675 

.8704 

30 

40 

.4950 

.5696 

1.7556 

.8689 

20 

50 

.4975 

.5735 

1.7437 

8675 

10 

30    00 

.5000 

.5774 

1.7321 

.8660 

00    60 

10 

.5025 

.5812 

1.7205 

.8646 

50 

20 

.5050 

.5851 

1.7090 

.8631 

40 

30 

.5075 

.5890 

1.6977 

.8616 

30 

40 

.5100 

.5930 

1.6864 

.8601 

20 

50 

.5252 

.5969 

1.6753 

.8587 

10 

31    00 

.5150 

.6009 

1.6643 

.8572 

00    59 

10 

.5175 

.6048 

1.6534 

.8557 

50 

20 

.5200 

.6088 

1.6426 

.8542 

40 

30 

.5225 

.6128 

1.6319 

.8526 

30 

40 

.5250 

.6168 

1.6212 

.8511 

20 

50 

.5275 

.6208 

1.6107 

.8496 

10 

N.  Cos. 

N.  Cot. 

N.  Tan. 

N.  Sin. 

/       o 

[  89  ] 


Sec.  1      NATURAL  TRIGONOMETRIC  FUNCTIONS 


FOUR-PLACE  VALUES  OF  TRIGONOMETRIC 

FUNCTIONS. 

o       / 

N.  Sin. 

N.  Tan. 

N.  Cot. 

N.  Cos. 

32     00 

.5299 

.6249 

1.6003 

.8480 

00    58 

10 

.5324 

.6289 

1.5900 

.8465 

50 

20 

.5348 

.6330 

1.5798 

.8450 

40 

30 

.5373 

.6371 

1.5697 

.8434 

30 

40 

.5398 

.6412 

1-5597 

.8418 

20 

50 

.5422 

.6453 

1.5497 

.8403 

10 

33     00 

.5446 

.6494 

1.5399 

.8387 

00    57 

10 

.5471 

.6536 

1.5301 

.8371 

50 

20 

.5495 

.6577 

1.5204 

.8355 

40 

30 

.5519 

.6619 

1.5108 

.8339 

30 

40 

.5544 

.6661 

1.5013 

.8323 

20 

50 

.5568 

.6703 

1.4919 

.8307 

10 

34    00 

.5592 

.6745 

1.4826 

.8290 

00    56 

10 

.5616 

.6787 

1.4733 

.8274 

50 

20 

.5640 

.6830 

1.4641 

.8358 

40 

30 

.5664 

.6873 

1.4550 

.8241 

30 

40 

.5688 

.6916 

1.4460 

.8225 

20 

50 

.5712 

.6959 

1.4370 

.8208 

10 

35    00 

.5736 

.7002 

1.4281 

.8192 

00    55 

10 

.5760 

.7046 

1.4193 

.8175 

50 

20 

.5783 

.7089 

1.4106 

.8158 

40 

30 

.5807 

.7133 

1.4019 

.8141 

30 

40 

.5831 

.7177 

1.3934 

.8124 

20 

50 

.5854 

.7221 

1.3848 

.8107 

10 

36    00 

.5878 

.7265 

1.3764 

.8090 

00    54 

10 

.5901 

.7310 

1.3680 

.8073 

50 

20 

.5925 

.7355 

1.3597 

.8056 

40 

30 

.5948 

.7400 

1.3514 

.8039 

30 

40 

.5972 

.7445 

1.3432 

.8021 

20 

50 

.5995 

.7490 

1.3351 

.8004 

10 

37    00 

.6018 

.7536 

1.3270 

.7986 

00    53 

10 

.6041 

.7581 

1.3190 

.7969 

50 

20 

.6065 

.7627 

1.3111 

.7951 

40 

30 

.6088 

.7673 

1.3032 

.7934 

30 

40 

.6111 

.7720 

1.2954 

.7916 

20 

50 

.6134 

.7766 

1.2876 

.7898 

10 

38     00 

.6157 

.7813 

1.2799 

.7880 

00    52 

10 

.6180 

.7860 

1.2723 

.7862 

50 

20 

.6202 

.7907 

1.2647 

.7844 

40 

30 

.6225 

.7954 

1.2572 

.7826 

30 

40 

.6248 

.8002 

1.2497 

.7808 

20 

50 

.6271 

.8050 

1.2423 

.7790 

10 

39    00 

.6293 

.8098 

1.2349 

.7771 

00    51 

10 

.6316 

.8146 

1.2276 

.7753 

50 

20 

.6338 

.8195 

1.2203 

.7735 

40 

30 

.6361 

.8243 

1.2131 

.7716 

30 

40 

.6383 

.8292 

1.2059 

.7698 

20 

50 

.6406 

.8342 

1.1988 

.7679 

10 

N.  Cos. 

N.  Cot. 

N.  Tan. 

N.  Sin. 

/       o 

[90] 


NATURAL  TRIGONOMETRIC  FUNCTIONS       Sec.  1 


FOUR-PLACE  VALUES  OF  TRIGONOMETRIC 

FUNCTIONS. 

o       / 

N.  Sin. 

N.  Tan. 

N.  Cot. 

N.  Cos. 

40    00 

.6428 

.8391 

1.1918 

.7660 

00    50 

10 

.6450 

.8441 

1.1847 

.7642 

50 

20 

.6472 

.8491 

1.1778 

.7623 

40 

30 

.6494 

.8541 

1.1708 

.7604 

30 

40 

.6517 

.8591 

1.1640 

.7585 

20 

50 

.6539 

.8642 

1.1571 

.7566 

10 

41     00 

.6561 

.8693 

1.1504 

.7547 

00    49 

10 

.6583 

.8744 

1.1436 

.7528 

50 

20 

.6604 

.8796 

1.1369 

.7509 

40 

30 

.6626 

.8847 

1.1308 

.7490 

30 

40 

.6648 

.8899 

1.1237 

.7470 

20 

50 

.6670 

.8952 

1.1171 

.7451 

10 

42    00 

.6691 

.9004 

1.1106 

.7431 

00    48 

10 

.6713 

.9057 

1.1041 

.7412 

50 

20 

.6734 

.9110 

1.0977 

.7392 

40 

30 

.6756 

.9163 

1.0913 

.7373 

30 

40 

.6777 

.9217 

1.0850 

.7353 

20 

50 

.6799 

.9271 

1.0786 

.7333 

10 

43    00 

.6820 

.9325 

1.0724 

.7314 

00    47 

10 

.6841 

.9380 

1.0661 

.7294 

50 

20 

.6862 

.9435 

1.0599 

.7274 

40 

30 

.6884 

.9490 

1.0538 

.7254 

30 

40 

.6905 

.9545 

1.0477 

.7234 

20 

50 

.6926 

.9601 

1.0416 

.7214 

10 

44    00 

.6947 

.9657 

1.0355 

.7193 

00    46 

10 

.6967 

.9713 

1.0295 

.7173 

50 

20 

.6988 

.9770 

1.0235 

.7153 

40 

30 

.7009 

.9827 

1.0176 

.7133 

30 

40 

.7030 

.9884 

1.0117 

.7112 

20 

50 

.7050 

.9942 

1.0058 

.7092 

10 

45     00 

.7071 

1.0000 

1.0000 

.7071 

00    45 

N.  Cos. 

N.  Cot. 

N.  Tan. 

N.  Sin. 

/       o 

[  91  ] 


TABLE  No.  3 

DECIMAL  EQUIVALENTS  AND    CIRCUMFERENCES 
AND  AREAS  OF  CIRCLES 


DECIMAL  EQUIVALENTS  OF  64ths 

The  decimal  fractions  printed  in  large  type  give  the  exact  value 
of  the  corresponding  fraction  to  the  fourth  decimal  place.  A  given 
decimal  fraction  is  rarely  exactly  equal  to  any  of  these  values,  and 
the  numbers  in  small  type  show  which  common  fraction  is  nearest 
to  the  given  decimal.  Thus,  lay  off  the  fraction  0.1330  in  64ths. 
The  nearest  decimal  fractions  are  0.1250  and  0.1406.  The  value  of 
any  fraction  in  small  type  is  the  mean  of  the  two  adjacent  fractions. 
In  this  instance  the  mean  fraction  is  0.1328,  and  as  0.1330  is  greater 
than  this,  0.1406  or  /¥  will  be  chosen.  In  the  same  manner  the 
nearest  64ths  corresponding  to  the  decimal  fractions  0.3670  and  0.8979 
are  found  to  be  f  f  and  ||,  respectively. 


Frac- 
tion. 

Decimal. 

Frac- 
tion. 

Decimal. 

Frac- 
tion. 

Decimal. 

Frac- 
tion. 

Decimal. 

eJ4 

.0078 
.0156 

U 

.2656 

U 

.5078 
.5156 

U 

j0 

A 

•0235 
.0313 

A 

I2813 

17 

•5235 
.5313 

II 

.7813 

.0391 

.2891 

•5391 

.7891 

B3f 

.0469 

H 

.2969 

1! 

.5469 

II 

.7969 

•0547 

•3047 

•5547 

.8047 

A 

.0625 

A 

.3125 

I95 

.5625 

U 

.8125 

.0703 

•3203 

•57°3 

.820.5 

et 

.0781 

ti 

.3281 

it 

.5781 

11 

.8281 

.0860 

.3360 

.5860 

.8360 

a3" 

.0938 

tt 

.3438 

II 

.5938 

§5 

.8438 

.1016 

•  35i6 

.6016 

.8516 

A 

.1094 

U 

.3594 

If 

.6094 

II 

.8594 

.1172 

.3672 

.6172 

.8672 

i 

.1250 

1 

.S750 

1 

.6250 

.8750 

A 

1328 
.1406 

If 

fgol 

II 

.6328 
.6406 

i! 

.8828 
.8906 

A 

•1485 
.1563 

U 

'.4063 

H 

.6485 
.6563 

ii 

.898  s 
.9063 

ii 

.1641 
.1719 

II 

.4141 
.4219 

U 

.6641 
.6719 

.9141 
.9219 

.1797 

•4297 

.6797 

.9297 

TS 

.1875 

TB 

.4375 

U 

.6875 

B 

.9375 

H 

•1953 
.2031 

IS 

•4453 
.4531 

ti 

•6953 
.7031 

Ii 

•9453 
.9531 

.2110 

.4610 

.7110 

.9610 

375 

.2188 

Si 

.4688 

H 

.7188 

31 

.9688 

.2266 

.4766 

.7266 

.9766 

41 

.2344 

U 

.4844 

i? 

.7344 

If 

.9844 

.2422 

.4922 

•7422 

.9922 

i 

.2500 

£ 

.5000 

2 

.7500 

1 

1.0000 

•2578 

.5078 

•7578 

[  94] 


CIRCUMFERENCES  AND  AREAS 


Sec.  1 


CIRCUMFERENCES  AND  AREAS 

OF  CIRCLES. 

Diam. 

Circum. 

Area. 

Diam. 

Circum. 

Area. 

j 

.0491 
.0982 
.1963 
.3927 

.0002 
.0008 
.0031 
.0123 

4f 
4j 
*| 

4j 

13.7445 
14  1372 
14.5299 
14.9226 

15.0330 
15.9043 
16.8002 
17.7206 

A 

.5890 
.7854 
.9817 
1.1781 

.0276 
.0491 
.0767 
.1104 

4J 
5 
5| 
51 

15.3153 
15.70&0 
16.1UU7 
16.4934 

18.6555 
19.6350 
20.6290 
21.6476 

$ 

1.3744 
1.5708 
1.7671 
1.9635 

.1503 
.1963 
.2485 
.3068 

5| 
5* 
5| 
5| 

16.8861 
17.2788 
17.6715 
18.0642 

22.6907 
23.7583 
24.8505 
25.9673 

1,5 
f 

2.1598 
2.3562 
2.5525 
2.7489 

.3712 
.4418 
.5185 
.6013 

51 
6 

N 

61 

18.4569 
18.8496 
19.2423 
19.6350 

27.1036 
28.2744 
29.4648 
30.6797 

i  .•> 
l1" 

!! 

2.9452 
3.1416 
3.5343 
3.9270 

.6903 
.7854 
.9940 
1.2272 

6 
6 
6 
6 

20.0277 
20.4204 
20.8131 
21.2058 

31.9191 
33.1831 
34.4717 
35.7848 

If 

l 
11 

4.3197 
4.7124 
5.1051 
5.4978       - 

1.4849 
1.7671 
2.0739 
2.4053 

61 

?! 

21.5985 
21.9912 
22.3839 
22.7766 

37.1224 
38.4846 
39.8713 
41.2826 

H 

2 
2* 
2i 

5.8905 
6.2832 
6.6759 
7.0686 

2.7612 
3.1416 
3.5466 
3.9761 

71 

7 

7i 

23.1693 
23.5620 
23.9547 
24.3474 

42.7184 
44.1787 
45.6636 
47.1731 

2 
2 
2 
2 

7.4613 
7.8540 
8.2467 
8.6394 

4.4301 
4.9087 
5.4119 
5.9396 

71 
8 
8* 
81 

24.7401 
25.1328 
25.5255 
25.9182 

48.7071 
50.2656 
51.8487 
53.4563 

Is 

3| 
3* 

9.0321 
9.4248 
9.8175 
10.2102 

6.4918 
7.0686 
7.6699 
8.2958 

8f 
1 

l! 

26.3109 
26.7036 
27.0963 
27.4890 

55.0884 
56.7451 
58.4264 
60.1322 

3 
3 
3 

3! 

10.6029 
10.9956 
11.3883 
11.7810 

8.9462 
9.6211 
10.3206 
11.0447 

S1 

9| 
91 

27.8817 
28.2744 
28.6671 
29.0598 

61.8625 
63.6174 
65.3968 
67.2008 

I1 

4 
4 

12.1737 
12.5664 
12.9591 
13.3518 

11.7933 
12.5664 
13.3641 
14.1863 

9| 
9J 
9| 
91 

29.4525 
29.8452 
30.2379 
30.6306 

69.0293 
70.8823 
72.7599 
74.6621 

[95] 


Sec.  1 


CIRCUMFERENCES  AND  AREAS 


CIRCUMFERENCES  AND  AREAS 

OF  CIRCLES. 

Diam. 

Circum. 

Area. 

Diam. 

Circum. 

Area. 

1 

31.0233 
31.4160 
31.8087 
32.2014 

76.589 
78.540 
80.516 
82.516 

15f 
15k 
15| 

48.3021 
48.6948 
49.0875 
49.4802 

185.661 
188.692 
191.748 
194.828 

oooo 

32.5941 
32.9868 
33.3795 
33.7722 

84.541 
86.590 
88.664 
90.763 

15 
16 

16 
16 

\ 

49.8729 
50.2656 
50.6583 
51.0510 

197  933 
201.062 
204.216 
207.395 

10 
11 
11 
11 

i:; 

34.1649 
34.5576 
34.9503 
35.3430 

92.886 
95.033 
97.205 
99.402 

16| 

16f 
16f 

51.4437 
51.8364 
52.2291 
52.6218 

210.598 
213.825 
217.077 
220.354 

11 
11 
11 
11 

35.7357 
36.1284 
36.5211 
36.9138 

101.623 
103.869 
106.139 
108.434 

I? 
17 

17 

i 

53.0145 
53.4072 
53.7999 
54.1926 

223.655 
226.981 
230.331 
233.706 

HI 
12 
12* 

121 

37.3065 
37.6992 
38.0919 
38.4846 

110.754 
113.098 
115.466 
117.859 

17 
17 
17 
17 

54.5853 
54.9780 
55.3707 
55.7634 

237.105 
240.529 
243.977 
247.450 

to  to  to  tc 

•' 

38.8773 
39.2700 
39.6627 
40.0554 

120.277 
122.719 
125.185 
127.677 

18* 
18f 

181 

56.1561 
56.5488 
56.9415 
57.3342 

250948 
254.470 
258.016 
261.587 

oowcoto 

\ 

40.4481 
40.8408 
41.2335 
41.6262 

130.192 
132.733 
135.297 
137.887 

18 
18 
18 
18 

57.7269 
58.1196 
58.5123 
58.9050 

265.183 
268.803 
272.448 
276.117 

co  co  co  co 

42.0189 
42.4116 
42.8043 
43.1970 

140.501 
143.139 
145.802 
148.490 

181 
19 

m 

191 

59.2977 
59.6904 
60.0831 
60.4758 

279.811 
283.529 
287.272 
291.040 

13J 
14 

14J 

43.5897 
43.9824 
44.3751 
44.7678 

151.202 
153.938 
156.700 
159.485 

19 
19 

19 

: 

• 

60.8685 
61.26t2 
61.6539 
62.0466 

294.832 
298.648 
302.489 
306.355 

14 
14 
14 

14 

45.1605 
45.5532 
45  9459 
46.3386 

162.296 
165.130 
167.990 
170.874 

191 
20 
20| 
201 

62.4393 
62.8320 
63.2247 
63.6174 

310.245 
314.160 
318.099 
322.063 

15 
15 
15 

" 

46.7313 
47.1240 
47.5167 
47.9094 

173.782 
176.715 
179.673 
182.655 

20S 
20* 
20 
20 

. 

1    ." 

64.0101 
64.4028 
64.7955 
65.1882 

326.051 
330.064 
334.102 
338.164 

[  96] 


CIRCUMFERENCES  AND  AREAS 


Sec.  1 


CIRCUMFERENCES  AND  AREAS 

OF  CIRCLES. 

Diam. 

Circum. 

Area. 

Diam. 

Circum. 

Area. 

201 
21 
2U 

m 

65.5809 
65  9736 
66.3663 
66.7590 

342.250 
346.361 
350.497 
354.657 

26| 
26£ 
264 

261 

82.8597 
83.2524 
83.6451 
84.0378 

546.356 
551547 
556.763 
562.003 

21| 
21* 
21f 
21| 

67.1517 
67.5444 
67.9371 
68.3298 

358.842 
363.051 
367.285 
371543 

261 

27 
27  i 
27* 

84.4305 
84.8232 
85.2159 
85.6086 

567.267 
572.557 
577.870 
583.209 

21f 
22 
22k 
22i 

687225 
69.1152 
69.5079 
69.9006 

375826 
380.134 
384.466 
388.822 

27| 
21h 
27| 
27| 

86.0013 
86.3940 
86  7867 
87.1794 

588.571 
593.959 
599.371 
604.807 

22f 
22  1 
22| 
221 

70.2933 
70.6860 
71.0787 
71.4714 

393.203 
397.609 
402.038 
406.494 

271 
28 
281 
28* 

87.5721 
87.9648 
88.3575 
88.7502 

610.268 
615.754 
621.264 
626.798 

221 
23 
23| 
23* 

71.8641 
72.2568 
72.6495 
73.0422 

410.973 
415.477 
420.004 
424.558 

28f 

28^ 
28f 
28| 

89.1429 
89.5356 
89.9283 
90.3210 

632.357 
637.941 
643.549 
649.182 

23f 
23^ 
23| 
231 

73.4349 
73.8276 
74.2203 
74.6130 

429.135 
433.737 
438.364 
443.015 

281 
29 
29J 
29* 

90.7137 
91.1064 
91.4991 
91.8918 

654.840 
660.521 
666.228 
671.959 

231 

24 
24  i 
241 

75.0057 
75.3984 
75.7911 
76.1838 

447.690 
452.390 
457.115 
461.864 

29f 

29| 
29f 
29f 

92.2845 
92.6772 
93.0699 
93.4626 

677.714 
683.494 
689.299 
695.128 

24| 
24| 
24f 
241 

76.5765 
76.9692 
77.3619 
77.7546 

466.638 
471.436 
476.259 
481.107 

291 
30 
30| 
30* 

93.8553 
94.2480 
94.6407 
95.0334 

700.982 
706.860 
712.763 
718.690 

241 
25 

25| 
25i 

78.1473 
78.5400 
78.9327 
79.3254 

485.979 
490.875 
495.796 
500.742 

ISf 

30f 
301 

95.4261 
95.8188 
96.2115 
96.6042 

724.642 
730.618 
738.619 
742.645 

25f 

25i 
25| 
25| 

79.7181 
80.1108 
80.5035 
80.8962 

505.712 
510.706 
515.726 
520.769 

301 
31 
3H 
31i 

96.9969 
97.38% 
97.7823 
98.1750 

748.695 
754.769 
760.869 
766.992 

251 
26 
26J 
26* 

81.2889 
81.6816 
82.0743 
82.4670 

525.838 
530.930 
536.048 
541.190 

31f 
314- 
31f 
311 

98.5677 
98.9604 
99.3531 
99.7458 

773.140 
779.313 
785.510 
791.732 

[97] 


Sec.  1 


CIRCUMFERENCES  AND  AREAS 


CIRCUMFERENCES  AND  AREAS 

OF  CIRCLES. 

Diam. 

Circum 

Area. 

Diam. 

Circum. 

Area. 

311 
32 
321 

100.1385 
100.5312 
100.9239 
101.3166 

797.979 
804.250 
810.545 
816.865 

37| 

37f 
37| 

117.417 
117.810 
118.203 
118.595 

1,097.118 
,104.469 
,111.844 
,119.244 

32 
32 
32 
32 

101.7093 
102.1020 
102.4947 
102.8874 

823.210 
829.579 
835.972 
842.391 

38* 
381 
381 

118.988 
119.381 
119.773 
120.166 

.126.669 
,134.118 
1,141.591 
1,149.089 

321 
33 

331 

103.280 
103.673 
104.065 
104.458 

848.833 
855.301 
861.792 
868.309 

38f 
381 
38f 
88| 

120.559 
120.952 
121.344 
121.737 

1,156.612 
1,164.159 
1,171.731 
1,179.327 

33 
33 
33 
33 

104.851 
105.244 
105.636 
106.029 

874.850 
881.415 
888.005 
894.620 

381 
39 
391 
39i 

122.130 
122.522 
122.915 
123.308 

1,186.948 
1,194.593 
1,202.263 
1,209.958 

33 
34 
34 
34 

\ 

106.422 
106  814 
107.207 
107.600 

901.259 
907  922 
914.611 
921.323 

39f 
391 
39  f 
39f 

123.700 
124.093 
124.486 
124.879 

1,217.677 
1,225.420 
1,233.188 
1,240.981 

34 
34 
34 
34 

107.992 
108.385 
108.778 
109.171 

928.061 
934.822 
941.609 
948.420 

391 
40 
401 
401 

125.271 
125.664 
126.057 
126.449 

1,248.798 
1,256.640 
1,264.510 
1,272.400 

341 
35 
351 
35i 

109.563 
109.956 
110.349 
110.741 

955.255 
962.115 
969.000 
975.909 

40| 

—  i 

126.842 
127.235 
127.627 
128.020 

1,280.310 
1,288.250 
1,296.220 
1,304.210 

35 
35 
35 
35 

111.134 
111.527 
111.919 
112.312 

982.842 
989.800 
996.783 
1,003.790 

401 
41 
411 
411 

128.413 
128.806 
129.198 
129.591 

1,312.220 
1,320.260 
1,328.320 
1,336.410 

35i 
36 
36 
36 

f 

112.705 
113.098 
113.490 
113.883 

1,010.822 
1,017.878 
1,024.960 
1,032.065 

41§ 
|}f 

129.984 
130.376 
130.769 
131.162 

1,344.520 
1,352.660 
1,360.820 
1,369.000 

36 
36 
36 
36 

114.276 
114.668 
115.061 
115.454 

1,039.195 
1,046.349 
1,053.528 
1,060.732 

411 
42 
421 
421 

131.554 
131.947 
132.340 
132733 

1,377.210 
1,385.450 
1,393.700 
1,401.990 

36 
37 
37 
37 

\  -- 

115.846 
116.239 
116.632 
117.025 

1,067.960 
1,075.213 
1,082.490 
1,089.792 

42f 

421 
42f 
42| 

133.125 
133.518 
133.911 
134.303 

1,410.300 
1,418.630 
1,426.990 
1,435.370 

t  98  ] 


CIRCUMFERENCES  AND  AREAS 


Sec.  1 


CIRCUMFERENCES  AND  AREAS 

OF  CIRCLES. 

Diam. 

Circum. 

Area. 

Diam. 

Circum. 

Area. 

421 

134,696 

1,443.770 

46 

146.084 

1,698.23 

43 
43| 

135.089 
135.481 

1,452.200 
1,460.660 

46 
46 

146.477 
146.870 

1,707.37 
1,716.54 

431 

135.874 

1,469.140 

46 

147.262 

1,725.73 

43f 

136.267 

1,477.640 

47 

147.655 

1,734.95 

43* 

136.660 

1,486.170 

47 

148.048 

1,744.19 

434 

137.052 

1,494.730 

47 

148.441 

1,753.45 

43| 

137.445 

1,503.300 

47| 

148.833 

1,762.74 

431 

137.838 

1,511.910 

47* 

149.226 

1,772.06 

44 

138.230 

1,520.530 

47 

149.619 

1,781.40 

44  i 

138.623 

1.529.190 

47 

150.011 

1,790.76 

44  i 

139.016 

1,537.860 

47 

150.404 

1,800.15 

44  f 

139.408 

1,546.56 

48 

150.797 

1,809.56 

44* 

139.801 

1,555.29 

48| 

151.189 

1,819.00 

44  f 

140.194 

1,564.04 

48 

151.582 

1,828.46 

44f 

140.587 

1,572.81 

48 

151.975 

1,837.95 

441 

140.979 

1,581.61 

48 

i 

152.368 

1,847.46 

45 

141.372 

1,590.43 

48 

.. 

152.760 

1,856.99 

45i 

141.765 

1,599.28 

48- 

: 

153.153 

1,866.55 

45* 

142.157 

1,608.16 

481 

153.546 

1,876.14 

45J 

142.550 

1,617.05 

49 

153.938 

1,885.75 

45* 

142.943 

1,625.97 

49  j 

• 

154.331 

1.895.38 

45| 

143.335 

1,634.92 

49 

154.724 

1,905.04 

45f 

143.728 

1,643.89 

48 

• 

155.116 

1,914.72 

451 

144.121 

1,652.89 

49 

155.509 

1,924.43 

46 

144.514 

1,661.91 

49 

155.902 

1.934.16 

46J 

144.906 

1,670.95 

49 

156.295 

1,943.91 

46J 

145.299 

1,680.02 

49 

156.687 

1,953.69 

40| 

145.692 

1,689.11 

50 

157.080 

1,963.50 

FUNDAMENTAL  UNITS,  MENSURATION, 

CONVERSION  FACTORS  AND 

METRIC  UNITS 


FUNDAMENTAL  UNITS 

The  electrical  units  are  derived  from  the  following  mechanical 
units: 

The  centimeter,  the  unit  of  length. 

The  gramme,  the  unit  of  mass. 

The  second,  the  unit  of  time. 

The  centimeter  equals  0.3937  of  an  inch,  or  one  thousand-millionth 
part  of  a  quadrant  of  the  earth. 

The  gramme  is  equal  to  15.432  grains,  the  mass  of  a  cubic  centi- 
meter of  water  at  4°  C. 

The  second  is  the  time  of  one  swing  of  the  pendulum,  making 
86,464.09  swings  per  day,  or  the  1-86400  part  of  a  mean  solar  day. 

MENSURATION 

Circumference  of  circle  whose  diameter  is  1  =ir  =  3. 14159265. 

Circumference  of  any  circle  =  diameter  Xir. 

Area  of  any  circle  =  (radius)2  Xir,  or  (diameter)2  X 0.7854. 

Surface  of  sphere  =  (diameter)2  XTT,  or  =  circumference  X diameter. 
Volume  of  sphere  =  (diameter)3  X0.5236,  or  =  surface  Xi  diameter. 

Area  of  an  ellipse  =  long  diameter  X  short  diameter  X  0.7854. 
7^  =  9.8696;  TT*  =  1.772454;  »  =  0.7854. 
»A  =  0.31831;  logx  =0.4971499. 
Basis  of  natural  log  r  =  2.7183,  log  e  =  0.43429. 

Modulus  of  natural  logarithm  M  =  j(~—  =  2.3026. 

144  Ib.  per  sq.  foot. 
51.7116  mm.  of  mercury. 


1  Ib.  per  sq.  inch 


2.30665  feet  of  water. 


0.072  ton  (short)  per  sq.  foot. 
0.0680415  atmosphere. 
'  One  mile  =  320  rod  =  1760  yards  =  5280  feet  =  63,360  inches. 
One  fathom  =  6  feet;  1  knot  =  6080  feet. 
1728  cubic  inches  =  1  cubic  foot. 
231  cubic  inches  =  1  liquid  gallon  =  0.134  cubic  foot. 
1  pound  avoirdupois  =  7000  grains  =  453.6  grammes. 
The  angle  of  which  the  arc  is  equal  to  the  radius,  a  Radian 
57.2958°. 

PHYSICAL  DATA 

The  equivalent  of  one  B.t.u.  of  heat  =  778  foot-pounds. 
The  equivalent  of  one  calorie  of  heat  =  426  kg-m.  =  3.968  B.  t.u. 
One  cubic  foot  of  water  weighs  62.355  pounds  at  62°  F. 
[  102] 


CONVERSION  FACTORS  Sec.  1 

One  cubic  foot  of  air  weighs  0.0807  pound  at  32°  F.  and  one 
atmosphere. 

One  cubic  foot  of  hydrogen  weighs  0.00557  pound. 

One  foot-pound  =  1.3562  X 107  ergs. 

One  horse-power  hour  =  33,000  X  60  foot-pounds. 

One  horse-power  =  33,000  foot-pounds  per  min.  =  550  foot-pounds 
per  second  =  746  watts  =  2545  B.t.u.  per  hour. 

Acceleration  of  gravity  (g)  =  32.2  feet  per  second. 
=  980  mm.  per  second. 

One  atmosphere  =  14.7  pounds  per  square  inch. 
=  2116  pounds  per  square  foot. 
=  760  mm.  of  mercury. 

Velocity  of  sound  at  0°  cent,  in  dry  air  =  332.4  meters  per  sec. 

=  1091  feet  per  sec. 

Velocity  of  light  in  vacuum  =  299,853  km.  per  sec. 
=  186,325  miles  per  sec. 

Specific  heat  of  air  at  constant  pressure  =  0.237. 

A  column  of  water  2.3  feet  high  corresponds  to  a  pressure  of  1 
pound  per  square  inch. 

Coefficient  of  expansion  of  gases  =  ?fg  =  0.00367. 

Latent  heat  of  water  =  79. 24. 

Latent  heat  of  steam  =  535. 9. 

CENTIGRADE  DEGREES.  To  convert  into  the  corresponding 
one  in  Fahrenheit  degrees,  multiply  by  9A  and  add  32.  To  convert 
it  into  the  one  in  Reaumur  degrees  multiply  by  Vs.  To  convert  It 
into  the  one  on  the  Absolute  scale,  add  273. 

FAHRENHEIT  DEGREES.  To  convert  into  the  one  in  Centigrade 
degrees,  subtract  32  and  then  multiply  by  6/9,  being  careful  about 
the  signs  when  the  reading  is  below  the  melting  point  of  ice.  To 
convert  it  into  the  one  in  Reaumur  degrees,  subtract  32  and  multiply 
by  4/9.  To  convert  it  into  the  one  on  the  Absolute  scale,  subtract 
32,  then  multiply  by  5A  and  add  273;  or  multiply  by  5,  add  2297, 
and  divide  by  9. 

ELECTRICAL  DATA 

{=unit  of  electric  power  =  h.  p.X746. 
=  current  X  volts  X  power  factor. 
=  foot  pounds  per  sec.  -f-  1.355. 
Joules,  W  =  work  done  =  watts  X  seconds. 
3412  B.t.u. 
2,654,536  foot-pounds. 


1  kw.  hour  = 


3.53  pounds  water  evaporated  at  212   F. 
22.8  pounds  water  raised  from  62°  to  212    F. 
0.235  pounds  carbon  oxidized  at  100  per  cent.  eff. 


METRIC  WEIGHTS  AND  MEASURES 
Linear 

1  meter  =  39.3704  inches  =  3.281  feet  =1.094  yards. 
Centimeter  (1-100  meter)  =  0.3937  inch. 
[  103  ] 


Sec.  1  METRIC  UNITS 

1  millimeter  (mm.)  =  0.03937  inch  =  39.37  mils. 
1  inch  =  25.3997  millimeters  =  0.083  foot  =  2.54  centimeters. 
1  kilometer  =  1,000  meters  or  3,281  feet  =  0.6213  mile. 
For  the  purpose  of  memory,  a  meter  may  be  considered  as  3  feet 
3H  inches. 

Surface  Measures 

Centare  (1  square  meter)  =  1,550  square  inches  =  10.764  square 
feet. 

Are  (100  square  meters)  =  119.6  square  yards. 
1  square  centimeter  =  0.155  square  inch  =  197,300  circular  mils. 
1  square  millimeter  =  0.00155  square  inch  =  1973  circular  mils. 
1  square  inch  =  6.451  square  centimeters  =  0.0069  square  foot. 
1  square  foot  =  929.03  square  centimeters  =  0.0929  square  meter. 

Weights 

Milligram  (1-1000  gram)  =  0.0154  grain. 

Centigram  (1-100  gram)  =  0.1543  grain. 

Decigram  (1-10  gram)  =  1.5432  grains. 

Gram  =  15.432  grains. 

Decagram  (10  grams)  =  0.3527  ounce. 

Hectogram  (100  grams)  =  3. 5274  ounces. 

Kilogram  (1,000  grams)  =2.2046  pounds. 

Myriagram  (10,000  grams)  =  22.046  pounds. 

Quintal  (100,000  grams)  =  220.46  pounds. 

Millier  or  tonne— ton  (1,000,000  grams)  =  2,204.6  pounds. 

Volumes 

Milliliter  (1-1000  liter)  =  0.061  cubic  inch. 
Centiliter  (1-JOO  liter)  =  0.6102  cubic  inch. 
Deciliter  (1-10  liter)  =  6. 1023  cubic  inches. 
Liter  =  1,000  cu.  cm.  =  61. 023  cubic  inches. 
Hectoliter  (100  liters)  =  2.838  bushels. 
Kiloliter  (1,000  liters)  =  1,308  cubic  yards. 

Liquid  Measures 

Milliliter  (1-1000)  =0.0338  fluid  ounce. 
Centiliter  (1-100  liter)  =  0.338  fluid  ounce. 
Deciliter  (1-10  liter)  =0.845  gill. 
Liter  =  0.908  quart  =  0.2642  gallon. 
Decaliter  (10  liters)  =  2.6418  gallons. 
Hectoliter  (100  liters)  =  26.418  gallons. 
Kiloliter  (1,000  liters)  =264.18  gallons. 


[  104  ] 


BIBLIOGRAPHY  Sec.  1 


BIBLIOGRAPHY 

Electrical  Meterman's  Handbook. 
American  Institute  of  Electrical  Engineers. 
Publications  of  Various  Wire  Manufacturers. 
Standard  Handbook  for  Electrical  Engineers. 
Foster's  Electrical  Engineer's  Pocketbook. 


[105] 


SECTION  2 

DISTRIBUTION  AND  TRANSMISSION 
LINE  SUPPORTS 


SECTION  2 

DISTRIBUTION  AND  TRANSMISSION 
LINE  SUPPORTS 


TABLE  OF  CONTENTS 

ARTICLE 

Wood  Poles 

General 1 


White  Cedar  or  Arbor  Vitae 2 

Chestnut 3 

Western  Red  Cedar 4 

Loblolly  Pine  Poles 5 

Western  Yellow  Pine 6 

Lodgepole  Pine  Poles 7 

Pole  Defects 8 

Butt  Rot 9 

Heart  Rot 10 

Season  Checks 11 

Wind  Shakes  and  Ring  Shakes 12 

Ring  Rot 13 

Cat  Faces 14 

Pole  Specifications 

General 15 

Specifications  for  Chestnut  Poles 16 

Specifications  for  Eastern  White  Cedar  Poles 17 

Specifications  for  Western  White  Cedar,  Red  Cedar,  Western 

Cedar,  Idaho  Cedar 18 

Specifications  for  Sawed  Redwood  Poles 19 

Specification  for  Yellow  Pine  Poles 20 

Specifications  for  Creosoted  Yellow  Pine  Poles 21 

Concrete  Poles 

General 22 

Steel  Reinforcing 23 

Concrete  Mixture 24 

Molding  Pole 25 

Hollow  Concrete  Poles 26 

Steel  Poles  and  Towers 27 

Patented  Steel  Poles 28 

Tubular  Steel  Poles 29 

Structural  Steel  Poles  and  Towers 30 

Flexible  Towers 31 

Outdoor  Substations , ...  32 

[109] 


WOOD  POLES 

1.  General.    Wood  poles  comprise  a  large  majority  of  the  poles 
in  use  upon  which  are  strung  aerial  conductors.     Approximately 
82  percent  of  the  wood  poles  in  use  in  this  country  are  either  cedar 
or  chestnut.     Cedar  represents  about  62  percent  and  chestnut  about 
20  percent  of  the  total.     The  remaining  18  percent  include  poles 
manufactured  from  every  specie  of  timber.* 

It  is  customary  to  purchase  poles  under  specifications  which 
usually  provide  for  their  dimensions,  etc.;  but,  in  general,  the 
logging  of  the  poles  is  entirely  neglected.  Inasmuch  as  it  is  the 
practice  of  a  number  of  companies  to  purchase  poles  on  the  stump 
the  following  data  on  logging  have  been  compiled,  covering  a  few 
of  the  more  important  species,  also  the  more  important  defects 
usually  found  in  timber  are  described. 

LOGGING 

2.  White  Cedar  or  Arbor  Vitae.     Northern  white  cedar  or  arbor 
vitae  is  a  common  swamp  tree  in  the  northeastern  and  lake  states 
and  in  Canada.     It  is  extensively  used  for  poles  as  it  grows  to  the 
required  form  and  size,  and  also  combines  the  desired  strength, 
lightness  and  durability.     Since  the  growth  of  this  species  is  so 
slow,  careful  logging  methods  will  not  bring  about  reproduction  that 
will  benefit  the  present  logger,  the  method  of  getting  out  white 
cedar  poles  is  determined  only  by  the  mechanical  and  topographical 
problems  involved. 

The  summer  and  winter  are  undoubtedly  the  best  seasons  in  which 
to  work  in  swamps  and  as  woods  labor  is  most  available  in  winter 
this  would  seem  to  be  the  better  of  the  two.  Further  because  of  the 
advantages  of  hauling  on  sleds,  the  late  fall  and  winter  offer  the 
best  conditions  for  cutting,  skidding  and  hauling,  and  these  opera- 
tions are  therefore  usually  carried  on  at  that  time.  Stumps  should 
not  be  cut  low;  and  at  least  above  the  characteristic  crook  near  the 
ground.  Poles  cut  and  peeled  during  the  late  fall  and  winter  and 
skidded  in  a  single  layer  well  off  the  ground  should  be  held  until 
the  first  of  May  before  shipping,  thus  insuring  a  decrease  in  freight 
weight  more  than  equal  to  the  expense  of  holding.  Poles  so  held 
will  also  gain  in  strength  and  durability. 

Green  arbor  vitae  poles  lose  the  larger  portion  of  their  moisture 
from  the  sapwood.  This  sapwood  is  very  thin,  consequently,  the 
loss  begins  immediately  after  exposure  to  favorable  seasoning  in- 
fluence, and  a  large  percent  of  the  moisture  is  lost  during  sixty  days 
of  fair  weather.  Spring  and  early  summer  offer  the  best  conditions 
for  maximum  seasoning  in  the  shortest  time. 

Checking  during  seasoning,  if  not  serious,  lias  no  particular  effect 
on  the  strength  of  the  pole  and  is  of  little  assistance  in  the  absorption 

*  U.  S.  Government  Statistics. 

[1111 


Sec.  2  WOOD  POLES 

of  preservatives.  The  greatest  checking  occurs  in  the  spring  and 
summer  cut  poles.  If  arbor  vitae  poles  are  properly  seasoned,  the 
sapwood  can  be  thoroughly  impregnated  with  creosote  in  the  open 
tank.  Fall  and  winter  cut  poles,  if  properly  skidded,  should  be  in 
satisfactory  condition  for  impregnation  by  the  following  June. 
If  skidded  several  layers  deep,  as  is  the  usual  custom,  they  will 
probably  have  to  be  seasoned  for  a  longer  period. 

3.  Chestnut.  The  chestnut-bearing  states  are  as  follows:  New 
Hampshire,  Vermont,  Massachusetts,  Connecticut,  New  York,  New 
Jersey,  Pennsylvania,  Ohio,  Maryland,  Delaware,  Virginia,  West 
Virginia,  Kentucky,  Tennessee  and  North  Carolina. 

The  best  chestnut  poles  are  cut  from  trees  grown  in  coves,  on 
lower  slopes,  and  in  level  country  on  deep,  well-drained,  loamy  soil. 
It  has  been  found  that  trees  grown  on  high  elevations  have  a  larger 


FIG.  20. — Butt  Rot  in  Eastern  White  Cedar  Pole.  Right^  hand  section  was 
cut  5  feet  from  Butt.  Middle  section  was  cut  10  feet  from*  Butt.  Left  hand 
section  shows  remainder  of  the  pole. 

taper  than  trees  grown  on  lower  levels.  A  considerable  difference 
has  been  found  where  the  elevation  varies  as  little  as  150  feet. 

The  exact  relation  between  the  inherent  specific  gravity  of  the 
wood  and  the  strength  of  the  pole  is  not  definitely  known.  It  is 
estimated,  however,  that  the  strength  varies  directly  with  the 
specific  gravity. 

Chestnut  timber  can  be  divided  into  two  general  classes — seed- 
grown  and  sprout-grown.  The  method  of  production  of  seed-grown 
trees  is  self-evident.  Sprout-grown  trees  are  trees  that  grow  from 
the  stumps  of  live  timber  which  has  been  cut  down.  Such  poles 
have  a  much  more  rapid  growth;  it  is  estimated  that  a  tree  of  suffi- 
cient size  from  which  to  cut  a  30  foot  pole  will  mature  when  grown 
from  a  stump  ten  years  sooner  than  a  tree  grown  from  seed.  The 
average  age  of  a  sprout-grown  tree  from  which  a  30-f t.  pole  can  be 
cut  is  forty  years,  and  of  those  grown  from  seed  to  a  similar  size, 
fifty  years. 

[112] 


WOOD  POLES 


Sec.  2 


In  cutting  chestnut-trees  it  is  most  important  to  consider  the  time 
at  which  the  timber  should  be  cut  and  the  method  of  cutting.  Un- 
doubtedly the  best  season  is  the  late  fall  and  winter.  This  is  due  to 
the  fact  that  most  vigorous  sprouts  originate  from  winter-cut 
stumps.  The  cost  of  logging  is  least.  The  season  is  not  conducive 
to  the  danger  of  an  attack  of  fungi.  The  poles  season  persistently 
and  have  the  advantage  of  a  gradual  rise  in  temperature  as  their 
moisture  contents  gradually  decrease.  The  slow  drying  rate  does 
not  result  in  serious  checking;  hence  the  poles  are  stronger. 

The  spring  and  summer  months  are  the  most  unfavorable  months 


FIG.  21. — Frequency  of  Butt  Rot  in  Eastern  White  Cedar  Poles. 

in  which  to  cut  timber,  as  it  dries  very  rapidly,  causing  large  season 
checks,  which  may  seriously  decrease  the  strength  of  the  pole. 

If  trees  are  cut  in  summer,  the  stumps  are  practically  killed,  and 
few,  if  any,  sprouts  will  originate  from  them.  Summer  cutting 
should,  therefore,  be  discouraged.  Moreover,  trees  cut  at  this 
season  are  subjected  to  decay  and  their  strength  may  be  materially 
affected  thereby. 

In  cutting  chestnut-trees,  consideration  should  be  given  to  cutting 
;  the  stumps  will  sprout.  This  is  accomplished 


in  such  a  manner  that 


[113] 


Sec.  2 


WOOD  POLES 


by  cutting  the  tree  as  near  the  ground  as  possible  and  giving  the  cut 
a  decided  pitch,  in  order  to  avoid  butt  rot  in  the  sprout-grown  poles. 

The  height  at  which  the  pole  is  cut  materially  affects  its  taper. 
If  the  tree  is  cut  low  the  basal  swelling  of  the  tree  will  be  included  in 
the  pole,  which,  where  the  tree  has  been  cut  one  (1)  foot  above  the 
ground,  increases  the  taper  in  circumference  as  much  as  five  inches 
over  its  circumference  if  cut  four  (4)  feet  above  the  ground. 

The  practice  of  dragging  poles  over  the  ground  for  long  distances 
should  be  discouraged  because  the  outer  layers  of  wood  are  sheared 
off  and  the  strength  of  the  poles  is  lessened.  Further,  a  pole  in  this 


FIG.  22. — Butt  Rot  in  Eastern  White  Cedar  Poles. 

condition  is  more  susceptible  to  decay  because  of  the  crevices  caused 
thereby  which  will  hold  water  and  spores. 

The  tops  of  trees  remaining  after  poles  are  cut  should  be  utilized 
for  cordwood,  as  this  increases  the  gross  value  of  the  timber. 

4.  Western  Red  Cedar.  The  regions  from  which  the  largest  pro- 
duction of  western  red  cedar  poles  are  secured  are  situated  in  the 
panhandle  of  the  State  of  Idaho,  or  Puget  Sound,  in  the  vicinity  of 
Bellingham  and  Everett,  Washington  and  along  the  lower  Columbia 
River.  Some  poles  are  logged  in  the  Grays  Harbor  region  of  the 
State  of  Washington. 

The  northern  portion  of  the  State  of  Idaho  produces  more  poles 

[114] 


WOOD  POLES 


Sec.  2 


than  any  similar  region  in  the  United  States.  West  Coast  poles  are 
logged  and  marketed  on  Puget  Sound.  Poles  obtained  from  the 
lower  Columbia  River  are  heavier  butted  and  weigh  more  than 
those  from  either  of  the  above  mentioned  regions.  The  taper  and 
other  properties  of  Columbia  River  poles  compare  favorably  with 
those  secured  from  other  regions,  but  Columbia  River  poles  are 
generally  free  from  butt  rot,  which  is  not  so  true  of  Idaho  cedar  poles. 
The  logging  and  piling  of  cedar  poles  is  generally  carried  on  in 
advance  of  the  logging  of  saw  timber,  the  pole  company  taking  the 
small  timber  before  the  fellers  of  saw  timber  advance  in  the  woods. 


FIG.  23.— Hollow  Knot  indicating  Heart  Rot  in  Eastern  White  Cedar  Pole. 

This  is  an  important  item  of  conservation,  since  in  ordinary  logging 
operations  where  pole  timber  is  not  removed  it  is  destroyed  by 
breakage  in  felling  the  larger  trees.  Poles  are  generally  removed 
from  the  woods  by  horse  team,  usually  to  storage  yards  or  to  the 
logging  railroad  of  the  logging  company,  over  which  they  are  trans- 
ported to  storage  yards  or  connecting  railroad  transportation. 

In  Idaho  and  on  Puget  Sound  many  poles  are  cut  by  ranchers  in 
the  clearing  of  land  and  are  finally  marketed  through  pole  companies. 

Poles  are  always  peeled  on  the  ground  immediately  after  felling 

[115] 


Sec.  2 


WOOD  POLES 


or  in  the  pole  yard  close  by.     As  a  rule  the  pole  cutter  works  alone, 
felling  the  timber,  slashing  the  branches  and  peeling. 

Pole  dealers  contend  that  winter  cut  poles  are  more  durable  and 
are  stronger  than  summer  cut  poles  because  the  sap  is  down  in  the 
winter,  the  moisture  content  is  less  and  the  poles  check  less  in  drying. 
However,  when  the  sap  is  down,  poles  are  harder  to  peel.  Users  pre- 
fer winter  cut  poles  and  generally  order  such.  The  pole  cutting 
season  in  Idaho  extends  from  May  1st  to  December  1st  and  often 
throughout  the  year.  On  Puget  Sound  poles  are  cut  at  any  time 
during  the  year,  preferably,  however,  during  the  winter  season  in 


FIG.  24.— Butt  Rot  in  Chestnut  Pole. 

order  to  meet  the  demands  of  the  trade  for  winter  cut  poles.  The 
season  of  cutting  affects  the  rate  of  drying  and  the  resulting  checking, 
but  otherwise  offers  no  convenience  to  the  cutter  or  dealer. 

On  Puget  Sound  it  is  customary  to  store  poles  for  water  shipments 
in  fresh  water  booms  -in  the  rivers  a  short  distance  from  the  Sound. 
This  fresh  water  storage  insures  against  the  attack  of  teredo  and 
other  salt  water  borers.  In  the  Inland  Empire  the  poles,  after  being 
peeled,  are  yarded  and  stored  on  the  ground  for  seasoning  or  they 
are  boomed  in  the  Inland  lakes  or  rivers.  Ground  storage  is  often 

[116] 


WOOD  POLES 


Sec.  2 


practiced  in  the  Puget  Sound  region,  if,  as  is  the  exception,  the  poles 
are  for  rail  distribution. 

Poles  for  cargo  shipments  on  Puget  Sound  are  gathered  from  the 
fresh  water  booms  and  are  built  into  cribs  in  the  salt  water.  Cribs 
are  built  in  tiers  and  contain  from  200  to  300  poles  sorted  for  length 
and  top  diameter.  Each  tier  is  laid  at  right  angles  to  the  one  below 
and  the  crib  generally  contains  five  or  six  tiers  of  poles.  In  loading 
for  water  shipments,  these  cribs  are  towed  to  the  side  of  the  vessel 
and  the  poles  are  loaded  direct. 

Poles  cannot  be  stored  in  the  salt  water  on  Puget  Sound  for  a 
long  period  because  of  the  attack  of  the  teredo.  During  the  months 
of  August  and  September  thirty  days'  storage  will  show  the  beginning 
of  teredo  attack,  while  during  the  winter  and  spring  seasons  they 
will  not  be  .active  for  from  four  to  six  months.  It  is  also  claimed 
that  the  teredo  is  much  more  active  on  mud  flats  than  on  gravel 
bottoms.  Therefore,  when  storage  grounds  are  in  salt  water,  the 


FIG.  25. — Heart  Rot  in  Chestnut  Pole. 

grounds  should  be  carefully  selected  and  the  poles  loaded  as  soon 
as  possible  after  storage. 

It  is  noticeable  that  specifications  for  cedar  poles  generally 
provide  that  the  poles  be  cut  from  live,  growing  cedar  timber. 
This  excludes  the  use  of  insect  or  fire-killed  pole  timber.  If  fire- 
killed  poles  are  cut  before  decay  or  insect  attack  begins,  they  are  not 
necessarily  inferior  unless  the"  killing  fire  injured  the  wood  of  the 
tree  in  a  visible  manner.  Fire-killed  poles  may  generally  be  con- 
sidered more  durable  and  more  economical  to  handle  as  they  season 
before  cutting.  Furthermore,  in  cases  where  the  bark  has  fallen, 
some  of  the  food  substances  in  the  sapwood  which  nourish  destruc- 
tive fungous  agencies  are  leached  out  by  rains,  and  decay  is  retarded. 
Unless  large  cracks  or  checks  develop,  it  is  doubtful  if  the  fire-killed 
timber  is  materially  weaker  than  green  cut  timber.  Many  fire- 
killed  or  dead  cedar  poles  are  accepted  under  specifications  requiring 
green  cut  poles,  the  inspectors  being  unable  to  distinguish  them. 
Such  poles  have  been  used  in  the  same  line  with  green  cut  poles  and 
have  given  equal  satisfaction.  There  is  no  well  defined  reason  for 

[117] 


Sec.  2  WOOD  POLES 

excluding  dead  poles  from  specifications,  provided  they  are  sound 
and  show  no  detrimental  defects,  such  as  insect  workings,  decay  of 
serious  checking.  Checking,  in  fact,  is  liable  to  be  more  severe  in 
green  logged,  air  seasoned  poles  than  in  fire-killed  poles,  provided 
the  bark  of  the  fire-killed  poles  was  not  directly  destroyed  by  the 
killing  fire. 

5.  Loblolly  Pine  Poles.  Loblolly  pine  is  a  probable  important 
future  source  of  poles  because  of  the  depletion  of  the  northern  white 
cedar  stand  and  because  of  the  destruction  of  chestnut  forests  by 
the  bark  disease.  Generally  speaking  loblolly  pine  is  not  as  good  a 
pole  timber  as  northern  white  cedar  or  chestnut,  as  it  is  likely  to  be 


FIG.  26. — Checks  and  Butt  Rot  in  Eastern  White  Cedar  Pole. 

very  knotty  and  trees  of  pole  form  are  not  so  common  in  pine  stands 
as  they  are  in  chestnut  and  cedar  stands. 

Trees  suitable  for  poles  will  be  found  more  often  in  medium  open 
old  field  stands.  The  more  open  stands  will  have  trees  that  are 
very  knotty  while  dense  stands  are  likely  to  produce  trees  compara- 
tively small  at  the  butt  and  of  little  taper.  It  is  advisable  to  cut 
loblolly  pine  poles  in  the  later  fall  or  winter  in  order  to  allow  as  much 
seasoning  as  possible  before  spring,  for  the  reason  that  spring  cut 
poles  are  very  liable  to  decay  during  seasoning  owing  to  the  un- 
evaporated  water  they  contain.  Loblolly  pine  poles  should  be  given 
a  preservative  treatment  before  using  and  before  such  treatment 

[118] 


WOOD  POLES 


Sec.  2 


they  should  be  placed  on  high  skids  with  space  between  all  poles, 
and  seasoned  for  several  months  or  else  artificially  seasoned. 

6.  Western  Yellow  Pine.  In  certain  parts  of  the  states  of  Cali- 
fornia, Nevada,  Utah,  Wyoming,  Colorado,  Arizona  and  New 
Mexico,  it  may  be  advisable  for  pole  using  companies  to  use  a  local 
timber  rather  than  bring  in  western  red  cedar  poles  by  rail.  Through- 
out this  region  there  is  a  great  deal  of  western  yellow  pine.  Such 
timber  will  furnish  poles  which  will  give  good~service  if  treated. 
The  following  statements  are  conclusions  from  an  investigation  in 
California.  Poles  of  western  yellow  pine  should  be  cut  from  hill- 
grown  timber  rather  than  from  valley-grown  timber. 


FIG.  27.— Ring  Shakes  in  Chestnut  Pcrte. 

Hill-grown  timber  grows  under  dryer  conditions  and  on  poorer 
soil;  hence  it  grows  much  more  slowly.  It  grows  remarkably 
straight  and  free  from  limbs.  It  has  a  uniform  taper,  which  is  less 
pronounced  and  better  adapted  to  poles  than  valley  grown  timber. 
This  particular  kind  of  timber  is  finer  grained,  stronger  and  contains 
much  more  heart  wood. 

Valley  Grown  Timber  is  more  liable  to  knottiness,  it  is  badly 
shaped,  rarely  shows  any  heartwood  and  usually  grows  so  rapidly 
that  the  annular  rings  do  not  hang  together.  Valley  grown  timber 
also  has  a  very  coarse  grain  and  if  grown  in  the  open,  has  a  large 
taper  and  many  small  limbs.  The  bole  in  such  timber  forms  a 
spool-like  shape  between  each  tree's  growth  or  whorl  or  limbs, 

[  H9  ] 


Sec.  2 


WOOD  POLES 


making  a  knotty  and  badly  appearing  pole.  The  butt  is  apt  to  be 
oversize  and  of  irregular  shape.  Where  such  timber  grows  closely 
together  it  often  has  many  limbs  well  toward  the  ground  but  these 
limbs  are  smaller  and  there  are  no  spool-like  depressions  between  the 
whorls.  Such  timber  makes  good  poles. 


FIG.  28.— Butt  Rot  and  Ring  Shakes  in  Eastern  White  Cedar  Pole. 


FIG.  29. — Ring  Rot  in  Chestnut  Pole. 
[120] 


WOOD  POLES 


Sec.  2 


Western  yellow  pine  has  a  short  life  below  ground.  As  a  pole 
timber  it  will  serve  but  two  or  three  years  untreated  and  if  set  green 
will  show  decided  decay  in  one  year.  Otherwise,  it  is  satisfactory. 
The  decay-resisting  power  can  be  controlled  by  the  use  of  preserv- 
atives which  the  timber  takes  successfully.  All  yellow  pine  poles 
should  be  treated  with  a  preservative  before  use. 


The  poles  should  be  well  seasoned  before  treatment  and  are  best 
treated  during  the  second  summer  after  cutting. 

The  poles  should  not  be  lumbered  during  the  summer  for  the 
reason  that  case  hardening,  due  to  rapid  drying,  causes  summercut 
poles  to  resist  the  entrance  of  preservatives  to  a  marked  degree. 
Poles  may  be  cut  at  any  other  season  but  preferable  during  the 

[121] 


Sec.  2  WOOD  POLES 

autumn,  after  September,  as  the  fall-cut  poles  absorb  the  preserv- 
ative far  more  readily  than  poles  cut  during  any  other  season. 

7.  Lodgepole  Pine  Poles.  In  the  Rocky  Mountain  and  Coast 
Ranges  there  are  at  present  abundant  stands  of  lodgepole  pine  which 
after  treatment  make  very  satisfactory  poles.  It  is  not  naturally 
durable  in  contact  with  the  ground,  but  it  takes  treatment  readily 
and  even  with  the  additional  cost  of  treatment  the  pine  pole  is 
comparatively  cheap.  In  many  regions  outside  the  region  where 
cedar  grows,  the  pine  may  be  made  to  last  longer  than  untreated 
cedar. 

Poles  should  be  cut  from  fairly  dense  stands  in  order  to  avoid 
the  knottiness  in  open  grown  trees  and  the  small  slender  poles 


FIG.  31.— Ant  Eaten  Butt  in  Eastern  White  Cedar  Pole. 

grown  in  very  thick  stands.  As  in  the  case  of  other  species,  lodge- 
pole  pine  poles  should  be  thoroughly  seasoned  before  treatment. 
Forest  fires  have  killed  many  stands  of  lodgepole  pine  and  on  many 
such  areas  the  timber  remains  entirely  sound  for  many  years  after 
the  fire.  Such  timber  is  thoroughly  seasoned  and  therefore  ready 
for  treatment  as  soon  as  cut.  When  both  sound  dead  timber  and 
live  timber  are  available  for  poles  which  are  to  be  treated,  the  sound 
dead  timber  is  usually  preferable  as  it  is  already  seasoned.  The 
prejudice  in  many  regions  against  the  use  of  dead  timber  is  based 
on  the  mistaken  assumption  that  there  is  some  inherent  difference 
in  wood  that  has  been  seasoned  on  the  stump  and  wood  that  has 
been  cut  when  green. 

[  122  ] 


WOOD  POLES  Sec.  2 

8.  Pole  Defects.     The  natural  defects,  some  of  which,  are  found 
in  all  kinds  of  timber  make  theoretical  calculations  of  strength  very 
uncertain.     It  is  of  utmost  importance  that  all  poles  be  subjected  to 
a  most  careful  inspection,  in  order  that  a  reasonably  uniform  product 
will  be  secured.     The  defects  which  may  occur  in  all  kinds  of  timber 
are  more  or  less  similar.     The  principal  ones  are  as  follows: 

(a)  Butt  Rot  (Art.  9) 

(b)  Heart  Rot  (Art.  10) 

(c)  Season  Checks  (Art.  11) 

(d)  Wind  shakes,  Ring  shakes,  etc.  (Art.  12) 

(e)  Ring  Rot  (Art.  13) 

(f)  Cat  Faces  (Art.  14) 

9.  Butt  Rot  (Figs.  20,  21,  22  and  24)  is  more  prevalent  in  some 
species  of  timber  than  in  others.     When  appearing  in  chestnut 
poles  it  is  usually  found  in  sprout  grown  trees  and  is  generally  the 


FIG.  32.— Ant  Eaten  Butt  in  Eastern  White  Cedar  Pole. 

result  of  careless  cutting  of  the  original  tree.  The  rot  should  be 
confined  to  a  small  proportional  part  of  the  cross-section  of  the  butt. 
It  should  not  extend  into  the  pole  a  very  great  distance  and  never  to 
above  what  will  be  the  ground  line. 

10.  Heart  Rot  (Figs.    23  arid  25)  is  usually  evidenced  by  small 
defective  knots  which  show  rot.     It  is  extremely  important  that 
such  knots  be  carefully  examined.     Fig.  25  shows  an  apparently 
perfectly  sound  chestnut  pole.     A  few  small  knots  about  0.5  inches 
in  diameter  indicated  evidence  of  heart  rot.     The  pole  was  cut  into 
and  decided  heart  rot  was  found  existing  for  about  15  feet  of  the 
pole's  length. 

11.  Season  Checks  (Fig.  26)  are  due  mostly  to  the  rate  at  which 
the  pole  is  seasoned.     The  more  rapid  the  seasoning,  the  more 

[  123  ] 


Sec.  2 


WOOD  POLES 


extensive  the  checks.  In  general,  they  may  be  said  to  decrease  the 
strength  of  the  pole.  The  greater  their  number,  or  the  larger  their 
size,  the  weaker  the  pole. 

12.  Wind  Shakes  and  Ring  Shakes.     (Figs.  27  and  28.)     Wind 
shakes  and  ring  shakes  are  caused  by  wind  strains  in  the  standing 
tree  or  by  careless  felling.     Such  defects  may  seriously  damage  the 
pole.     Defects  which  are  incipient  in  green  poles  sometimes  extend 
until  they  form  a  split  anywhere  from  1  to  9  feet  long.     The  extent 
of  such  defects  should  be  carefully  examined,  in  order  that  the 
strength  of  accepted  poles  will  not  be  materially  reduced. 

13.  Ring  Rot.     (Fig.  29.)  takes  the  form  of  a  ring  and  is  usually 
in  evidence  at  the  butt  of  the  pole.     When  such  rot  exists,  it  should 


FIG.  33. — Ant  Eaten  Butt  in  Chestnut  Pole. 

not  be  extensive  in  character  and  should  not  extend  into  the  pole  for 
too  great  a  distance. 

14.  Cat  Faces  (Figs.  30A  and  B)  are  the  result  of  an  injury  to  a  tree 
over  which  the  bark  never  heals.  The  wood  at  this  point  dries  out 
and  is  not  covered,  except  at  the  edges  of  a  wound,  by  new  wood  or 
bark  and  therefore  becomes  dead  wood.  Sometimes  there  is  also 
a  swelling  at  this  point.  It  is  exposed  to  fungus,  insect  attack,  and 
weathering,  and  therefore,  after  a  pole  has  been  cut  and  peeled,  the 

[  124] 


WOOD  POLES  Sec.  2 

cat  face  shows  as  a  weathered  place,  which  it  may  not  be  possible 
to  eliminate  by  shaving.  However,  if  no  decay  has  started  in  the 
cat  face,  the  pole  should  not  be  rejected.  If  any  decay,  which  has 
started,  can  be  shaved  off  and  down  into  sound  wood  without 
materially  decreasing  the  pole  diameter  at  this  point,  the  pole  should 
not  be  rejected.  A  pole  that  shows  bright  sap  just  after  shaving 
with  one  or  more  cat  faces,  will,  after  it  has  seasoned  a  year  or  more, 
present  practically  the  same  appearance  all  over. 

POLE  SPECIFICATIONS: 

15.  General.  The  preparation  of  specifications  covering  all  kinds 
of  timber  would  be  extremely  lengthy.  Therefore,  detail  specifica- 
tions are  given  for  the  more  generally  used  timbers  only. 

The  selection  of  the  proper  kind  of  timber,  from  which  poles  should 
be  manufactured,  is  governed  entirely  by  the  locality  in  which  they 
are  to  be  used.  Any  available  timber  may  be  used  provided  it 
develops  sufficient  mechanical  strength.  The  theoretical  strength 
of  a  pole  is  dependent  on  the  diameter  of  the  butt,  the  modulus  of 
rupture  of  the  timber,  and  the  taper.  The  natural  defects  found  in 
all  kinds  of  timber  makes  it  necessary  that  they  be  subjected  to  very 
careful  inspection,  in  order  that  incipient  rot,  bad  knots,  etc.  do  not 
decrease  their  strength  to  a  dangerous  degree. 

The  theoretical  calculation  of  the  strength  of  a  wood  pole  (Sec. 
8,  Art.  18)  develops  the  following  important  facts. 

A  pole  will  break  where  its  diameter  is  1.5  times  the  diameter  at 
which  the  load  is  applied.  (The  critical  diameter.) 

When  the  taper  of  a  pole,  with  a  given  top  diameter,  is  uniform 
and  of  such  a  value  that  the  ground  line  diameter  is  greater  than  the 
critical  diameter,  the  strength  of  the  pole  is  constant  and  independent 
of  its  height;  when  the  height  of  such  a  pole  is  reduced  until  its 
diameter  at  the  ground  line  is  less  than  the  critical  diameter,  the 
strength  will  vary,  depending  upon  its  height  and  its  diameter  at  the 
ground  line. 

When  the  diameter  at  the  ground  line  is  greater  than  the  critical 
diameter,  a  certain  decrease  in  ground  line  diameter,  due  to  rot, 
may  occur  without  decreasing  the  strength  of  the  pole;  this  amount 
of  decrease  is  dependent  only  on  the  taper  of  the  pole. 

From  the  above,  it  follows  that  pole  specifications  should  be  such 
that  the  greatest  possible  taper  will  be  secured,  and  if  the  kind  of 
timber  is  such  that  small  tapers  are  natural  the  butt  diameter  should 
be  the  controlling  factor.  Where  larger  tapers  are  natural  the  butt 
and  top  diameters  must  be  considered. 

16.  SPECIFICATIONS  FOR  CHESTNUT  POLES.* 

To  determine  the  character  of  poles  to  be  used,  pole  lines  may  be 
divided  into  the  three  following  classes : 

Class  "A":  for  heavy  transmission  lines  or  heavy  distribution 
lines. 

*  National  Electric  Light  Association  Specification.       -,--• 

[125] 


Sec.  2 


WOOD  POLES 


Class  "B":  for  light  transmission  lines  or  ordinary  distribution 
lines. 

Class  "C":  for  very  light  distribution  lines  or  light  secondary 
lines. 

The  purchasing  company  is  to  have  the  right  to  make  such  in- 
spections of  the  poles  as  it  may  desire.  The  inspector  of  the  pur- 
chasing company  shall  have  the  power  to  reject  any  pole  which  is 
defective  in  any  respect.  Inspection,  however,  shall  not  relieve  the 
manufacturer  from  furnishing  perfect  poles. 

Any  imperfect  poles  which  may  be  discovered  before  their  final 
acceptance  shall  be  replaced  immediately  upon  the  requirement  of 
the  purchasing  company,  notwithstanding  that  the  defects  may  have 
been  overlooked  by  the  inspector.  If  the  requirements  of  these 
specifications  are  not  fulfilled  when  the  poles  are  offered  for  final 
acceptance,  not  only  shall  the  purchasing  company  have  the  right 
to  reject  the  poles,  but  the  expense  of  inspection  of  such  defective 
poles  shall  be  borne  by  the  manufacturer. 

All  poles  shall  be  subject  to  inspection  by  the  purchasing  company, 
either  in  the  woods,  where  the  trees  are  felled,  or  at  any  point  of 
shipment  or  destination.  Any  pole  failing  to  meet  all  the  require- 
ments of  these  specifications  may  be  rejected. 

All  poles  shall  be  of  the  best  quality  live  white  chestnut,  squared 
at  both  ends,  reasonably  straight,  well  proportioned  from  butt  to 
top,  peeled  and  with  knots  trimmed  close. 

The  dimensions  of  poles  shall  be  according  to  the  following  table, 


DIMENSIONS  OF  POLES  IN  INCHES. 

CLASSES. 

Length 
of 

A 

B 

C 

Poles. 

Top. 

6'  from 
Butt. 

Top. 

6'  from 
Butt. 

Top. 

6'  from 
Butt. 

25 

20 

30 

30 

24 

40 

22 

36 

20 

33 

35 

24 

43 

22 

40 

20 

36 

40 

24 

45 

22 

43 

20 

40 

45 

24 

48 

22 

47 

20 

43 

50 

24 

51 

22 

50 

20 

46 

55 

22 

54 

22 

53 

20 

49 

60 

22 

57 

22 

56 

65 

22 

60 

22 

59 

70 

22 

63 

22 

62 

75 

22 

66 

22 

65 

80 

22 

70 

22 

69 

85 

22 

73 

22 

72 

90 

22 

76 

22 

75 

[  126] 


WOOD  POLES 


Sec.  2 


the  "Top"  measurements  being  the  circumference  at  the  top  of  the 
pole,  and  the  "Butt"  measurement  being  the  circumference  six  feet 
(6'  0")  from  the  butt. 

17.  SPECIFICATIONS  FOR  EASTERN  WHITE 
CEDAR  POLES.* 

The  material  desired  under  these  specifications  consists  of  poles 
of  the  best  quality  of  either  seasoned  or  live  green  cedar  of  the  di- 
mensions hereinafter  specified.  Seasoned  poles  shall  have  preference 
over  green  poles  provided  they  have  not  been  held  for  seasoning  long 
enough  to  have  developed  any  of  the  timber  defects  hereinafter 
referred  to.  All  poles  shall  be  reasonably  straight,  well  proportioned 
from  butt  to  top,  shall  have  both  ends  squared,  the  bark  peeled  and 
all  knots  and  limbs  closely  trimmed. 

Dimensions 

The  dimensions  of  the  poles  shall  be  in  accordance  with  the  fol- 
lowing table,  the  "top"  measurement  being  the  circumference  at  the 
top  of  the  pole  and  the  "butt"  measurement  the  circumference  six 
(6)  feet  from  the  butt. 


MINIMUM  DIMENSIONS  OF  POLES  IN  INCHES    (CIR- 
CUMFERENCE) 

Length 

Poles. 

(Feet.) 

CLASSES. 

A 

B 

C 

Top. 

6'  from 
Butt. 

Top. 

6'  from 
Butt. 

Top. 

6'  from 
Butt. 

25 
30 
35 
40 
45 
50 
55 
60 

24 
24 
24 
24 
24 
24 
24 

40 
43 
47 
50 
53 
56 
59 

22 
22 
22 
22 
22 
22 
22 
22 

32 
36 
38 
43 
47 
50 
53 
56 

it 

18 
18 
18 

18  j 
18, 

! 

30 
33 
36 
40 
43 
46 
49 

When  the  dimension  at  the  butt  is  not  given  the  poles  shall  be 
reasonably  well  proportioned  throughout  their  entire  length. 

The  dimension  requirement  at  the  six  (6)  foot  mark  shall  be  rigidly 
followed  in  all  cases.  Class,  A,  B,  and  C  Poles  may  have  top  cir- 


*  National  Electric  Light  Association  Specification. 

[  127] 


Sec.  2  WOOD  POLES 

cumference  not  more  than  one  half  (l/$)  inch  less  than  those  shown 
in  the  preceding  table.  No  pole  shall  be  over  six  (6)  inches  longer  or 
three  (3)  inches  shorter  than  the  length  for  which  it  is  accepted;  if 
any  pole  be  more  than  six  inches  longer  than  is  required  it  shall  be 
cut  back. 

Quality  of  Timber 

Dead  Poles.     The  wood  of  a  dead  pole  is  grayish  in  color.     The 

Eresence  of  a  black  line  on  the  edge  of  the  sapwood  (as  seen  on  the 
utt)  also  shows  that  a  pole  is  dead.  No  dead  poles,  and  no  poles 
having  dead  streaks  covering  more  than  one  quarter  of  their  surface 
shall  be  accepted  under  these  specifications.  Poles  having  dead 
streaks  covering  less  than  one  quarter  of  their  surface  shall  have  a 
circumference  greater  than  otherwise  required.  The  increase  in 
the  circumference  shall  be  sufficient  to  afford  a  cross-sectional  area 
of  sound  wood  equivalent  to  that  of  sound  poles  of  the  same  class. 

Fire  Killed  or  River  Poles.  No  dark  red  or  copper  colored  poles, 
which  when  scraped  do  not  show  good  live  timber  shall  be  accepted 
under  these  specifications. 

Twisted,  Checked  or  Cracked  Poles.  No  poles  having  more  than 
one  complete  twist  for  every  twenty  (20)  feet  in  length,  no  cracked 
poles  containing  large  season  checks  shall  be  accepted  under  these 
specifications. 

"Cat  Faces."  No  poles  having  "cat  Faces,"  unless  they  are  small 
and  perfectly  sound  and  the  poles  have  an  increased  diameter  at 
the  "cat  face,"  and  no  poles  having  "cat  faces"  near  the  six  (6)  foot 
mark  or  within  ten  (10)  feet  of  their  tops,  shall  be  accepted  under 
these  specifications. 

Shaved  Poles.  No  shaved  poles  shall  be  accepted  under  these 
specifications. 

Miscellaneous  Defects.  No  poles  containing  sap  rot,  evidence 
of  internal  rot  as  disclosed  by  a  careful  examination  of  all  black 
knots,  hollow  knots,  woodpecker  holes,  or  plugged  holes;  and  no 
poles  showing  evidences  of  having  been  eaten  by  ants,  worms  or 
grubs  shall  be  accepted  under  these  specifications,  except  that  poles 
containing  worm  or  grub  marks  below  the  six  (6)  foot  mark  will  be 
accepted. 

Crooked  Poles.  No  poles  having  a  short  crook  or  bend,  a  crook 
or  bend  in  two  planes  or  a  reverse  curve  shall  be  accepted  under 
these  specifications.  The  amount  of  sweep,  measured  between  the 
six  foot  mark  and  the  top  of  the  pole,  that  may  be  present  in  poles 
acceptable  under  these  specifications,  is  shown  in  the  following 
table: 

35  foot  poles  shall  not  have  a  sweep  over  10)^  inches. 
40  foot  poles  shall  not  have  a  sweep  over  12  inches. 
45  foot  poles  shall  not  have  a  sweep  over  9  inches. 
50  foot  poles  shall  not  have  a  sweep  over  10  inches. 
55  foot  poles  shall  not  have  a  sweep  over  11  inches. 
60  foot  poles  shall  not  have  a  sweep  over  12  inches. 

[  128] 


WOOD  POLES 


Sec.  2 


Defective  Tops.  Poles  having  tops  of  the  required  dimensions 
must  have  sound  tops.  Poles  having  tops  one  (1)  inch  or  more 
above  the  requirements  in  circumference  may  have  one  (1)  pipe 
rot  not  more  than  one-half  (J^)  inch  in  diameter.  Poles  with  double 
tops  or  double  hearts  shall  be  free  from  rot  where  the  two  parts  or 
hearts  join. 

Defective  Butts.  No  poles  containing  ring  rot  (rot  in  the  form  of  a 
complete  or  partial  ring)  shall  be  accepted  under  these  specifications. 

Poles  having  hollow  hearts  may  be  accepted  under  the  conditions 
shown  in  the  following  table: 


Add  to  Butt  Requirements 

Average  Diameter 

of 

of 

of 

of  Rot. 

25  and  30 

35,  40  and  45 

50,  55,  60  and  65 

foot  Poles. 

foot  Poles. 

foot  Poles. 

2  inches 

Nothing 

Nothing 

Nothing 

3  inches 

1  inch 

Nothing 

Nothing 

4  inches 

2  inches 

Nothing 

Nothing 

5  inches 

3  inches 

1  inch 

Nothing 

6  inches 

4  inches 

2  inches 

1  inch 

7  inches 

Reject 

4  inches 

2  inches 

8  inches 

Reject 

6  inches 

3  inches 

9  inches 

Reject 

Reject 

4  inches 

10  inches 
11  inches 

Reject 
Reject 

Reject 
Reject 

5  inches 
7  inches 

12  inches 

Reject 

Reject 

9  inches 

13  inches 

Reject 

Reject 

Reject 

Scattered  rot,  unless  it  is  near  the  outside  of  the  pole  may  be 
estimated  as  being  the  same  as  heart  rot  of  equal  area. 

"Wind  Shakes."  Poles  with  cup  shakes  (Checks  in  the  form  of 
rings)  which  also  have  heart  or  star  checks  may  be  considered  as 
equal  to  poles  having  hollow  hearts  of  the  average  diameter  of  the 
cup  shakes. 

Inspection.  All  poles  shall  be  subject  to  inspection  by  the 
purchaser's  representative,  either  in  the  woods  where  the  trees  are 
felled,  or  at  any  point  of  shipment,  or  destination.  Each  pole  thus 
inspected  shall  be  marked  according  to  its  length  and  class  with  a 
marking  hammer,  by  the  purchaser's  representative.  All  poles  fail- 
ing to  meet  these  specifications  shall  be  rejected. 

18.  SPECIFICATIONS  FOR  WESTERN  WHITE  CEDAR,  RED 
CEDAR,  WESTERN  CEDAR,  IDAHO  CEDAR.* 

General. 

The  material  desired  under  these  specifications  consists  of  poles 
and  guy  stubs  of  the  best  quality  of  either  seasoned  or  live  green 

*  American  Telephone  &  Telegraph  Co.  Specification. 
5  [  129  ] 


Sec.  2 


WOOD  POLES 


cedar  of  the  dimensions  hereinafter  specified.  The  poles  covered 
by  these  specifications  are  of  Western  White  Cedar,  otherwise  known 
as  red  cedar,  western  cedar,  or  Idaho  cedar.  Seasoned  poles  shall 
have  preference  over  green  poles  provided  they  have  not  been  held 
for  seasoning  long  enough  to  have  developed  any  of  the  timber 
defects  hereinafter  referred  to.  All  poles  shall  be  reasonably  straight, 
well  proportioned  from  butt  to  top,  shall  have  both  ends  squared, 
sound  tops,  the  bark  peeled,  and  all  knots  and  limbs  closely  trimmed. 

Dimensions. 

The  dimensions  of  the  poles  shall  be  in  accordance  with  the  fol- 
lowing table,  the  "top"  measurement  being  the  circumference  at 
the  top  of  the  pole  and  the  "butt"  measurement,  the  circumference 
six  (6)  feet  from  the  butt.  The  dimensions  given  are  the  minimum 
allowable  circumferences  at  the  point  specified  for  measurement  and 
are  not  intended  to  preclude  the  acceptance  of  poles  of  larger  di- 
mensions. 

When  the  dimension  at  the  butt  is  not  given,  the  poles  shall  be 
reasonably  well  proportioned  throughout  their  entire  length. 
No  pole  shall  be  over  six  (6)  inches  longer  or  three  (3)  inches 
shorter  than  the  length  for  which  it  is  accepted.  If  any  pole  is 
more  than  six  (6)  inches  longer  than  is  required  it  shall  be  cut 
back. 


MINIMUM  DIMENSIONS  OF  POLES  IN  INCHES. 

Length  of 
Poles. 
(Feet.) 

CLASSES. 

A 

B 

C 

(Minimum    Top 
circumference  28) 
Circumference 
6  feet  from 
Butt 

(Minimum    Top 
Circumference  25) 
Circumference 
6  feet  from 
Butt 

(Minimum    Top 
Circumference  22) 
Circumference 
6  feet  from 
Butt 

20 
22 
25 
30 
35 
40 
45 
50 
55 
60 
65 

30 
32 
34 
37 
40 
43 
45 
47 
49 
52 
54 

28 
30 
31 
34 
36 
38 
40 
42 
44 
46 
48 

26 
27 
28 
30 
32 
34 
36 
38 
40 
41 
43 

[  130] 


WOOD  POLES  Sec.  2 

Quality  of  Timber 

Dead  Poles.  No  dead  poles  and  no  poles  having  dead  streaks 
covering  more  than  one  quarter  of  their  surface  shall  be  accepted 
under  these  specifications.  Poles  having  dead  streaks  covering 
less  than  one-quarter  of  their  surface  shall  have  a  circumference 
greater  that  otherwise  required.  The  increase  in  the  circumference 
shall  be  sufficient  to  afford  a  cross  sectional  area  of  sound  wood 
equivalent  to  that  of  sound  poles  of  the  same  class. 

Twisted,  Checked  or  Cracked  Poles.  No  poles  having  more  than 
one  complete  twist  for  every  twenty  (20)  feet  in  length,  no  cracked 
poles,  and  no  poles  containing  large  season  checks,  shall  be  accepted 
under  these  specifications. 

Crooked  Poles.  No  poles  having  a  short  crook  or  bend,  a  crook 
or  bend  in  two  planes,  or  a  reverse  crook  or  bend  shall  be  accepted 
under  these  specifications.  The  amount  of  sweep  measured  between 
the  six  (6)  foot  mark  and  the  top  of  the  pole,  shall  not  exceed  one 
(1)  inch  to  every  six  (6)  feet  in  length. 

"Cat  Faces."  No  poles  having  "cat  faces"  unless  they  are  small 
and  perfectly  sound,  and  the  poles  have  an  increased  diameter  at 
the  "cat  face,"  and  no  poles  having  "cat  faces"  near  the  six  (6)  foot 
mark,  or  within  ten  (10)  feet  of  their  tops  shall  be  accepted  under 
these  specifications. 

Shaved  Poles.  No  shaved  poles  shall  be  accepted  under  these 
specifications. 

Wind  Shakes.  No  poles  shall  have  cup  shakes  (checks  in  the 
form  of  rings)  containing  heart  or  star  shakes  which  enclose  more 
than  ten  (10)  percent  of  the  area  of  the  butt. 
'  Butt  Rot.  No  poles  shall  have  butt  rot  covering  in  excess  of 
ten  (10)  percent  of  the  total  area  of  the  butt.  The  butt  rot,  if  pres- 
ent, must  be  located  close  to  the  center  in  order  that  the  pole  may 
be  accepted. 

Knots.  Large  knots,  if  sound  and  trimmed  close  shall  not  be 
considered  a  defect.  No  poles  shall  contain  hollow  or  rotten  knots. 

Miscellaneous  Defects.  No  poles  containing  sap  rot,  wood- 
pecker holes  or  plugged  holes,  and  no  poles  showing  evidences  of 
having  been  eaten  by  worms,  ants,  or  grubs  shall  be  accepted  under 
these  specifications. 

19.  SPECIFICATIONS  FOR  SAWED  REDWOOD  POLES* 

General.  The  material  desired  under  these  specifications  consists 
of  poles  of  redwood  (Sequois  Sempervirens)  sawed  to  shape  as  here- 
inafter set  forth. 

Quality  of  Timber  and  Workmanship.  All  poles  shall  be  of  sound 
Number  One  Common  Redwood ;  they  should  be  reasonably  straight 
and  well  sawn. 

*  American  Telegraph  &  Telephone  Co.  Specification. 

[131] 


Sec.  2 


WOOD  POLES 


Dimensions.     The  dimensions  of  the  poles  shall  be  in  accordance 
with  the  following  table: 


A 

B 

Length  in 
Feet. 

Top.                    Butt. 

Top.                    Butt. 

24 

6' 

x6' 

6" 

6" 

4 

x  6' 

4' 

x  6" 

25 

7' 

x7' 

10" 

10" 

6 

x  6' 

9' 

x9" 

30 

7' 

x7' 

11" 

11" 

6 

x6' 

10' 

x  10" 

35 

T 

x7' 

12" 

12" 

6 

x  6' 

11' 

x  11" 

40 

r 

x7' 

13" 

13" 

6 

xfi' 

12' 

x  12" 

45 

T 

x7' 

14" 

14" 

6 

x  6' 

13' 

x  13" 

50 

r 

x  7' 

15£" 

15^" 

6 

x6' 

14' 

x  14" 

The  sectional  dimensions  of  the  sawn  poles  shall  not  be  more  than 
one-quarter  (24)  of  an  inch  under  or  three  quarters  (%)  of  an  inch 
over  the  dimensions  specified  in  the  above  table.  No  pole  shall  be 
more  than  three  inches  longer  or  shorter  than  the  lengths  required 
in  the  above  table. 

Sap  wood.  No  pole  shall  have  sapwood  covering  more  than  four 
(4)  percent  of  the  area  of  all  the  surfaces.  No  pole  shall  have 
sapwood  for  a  distance  of  more  than  eight  (8)  feet  from  the  top. 
No  sapwood  shall  be  deeper  than  one  (1)  inch  at  any  point. 

Plugged  Holes.     No  poles  shall  contain  plugged  holes. 

Cracked  Poles.  No  pole  shall  contain  cracks  transverse  to  the 
length  of  the  pole. 

Checked  Poles.     No  pole  shall  contain  large  season  checks. 

Wind  Shakes.  No  pole  shall  contain  wind  shakes  including  in 
excess  of  ten  (10)  percent  of  the  area  of  the  butt. 

Knots.  No  pole  shall  contain  loose,  hollow,  or  rotten  knots, 
black  or  red  knots  shall  be  carefully  examined  for  internal  rot. 

In  4"  x  6"  poles  sound  knots  with  a  diameter  smaller  than  one 
(1)  inch  may  be  present  in  any  number.  No  4"  x  6"  pole  shall  be 
accepted  which  contains  more  than  one  sound  knot  in  each  five 
superficial  feet  having  a  diameter  of  one  (1)  inch  or  more,  or  which 
contains  any  knots  with  a  diameter  greater  than  one  and  one  half 
(\y2)  inch. 

In  all  other  sizes  of  poles  covered  by  these  specifications  sound 
knots  with  a  diameter  smaller  than  one  and  one  half  (11A)  inches 
may  be  present  in  any  number.  No  pole  shall  be  accepted  which 
contains  more  than  one  sound  knot  in  each  five  superficial  feet 
having  a  diameter  of  one  and  one  half  (1^)  inches  or  more,  or  which 
contains  any  knots  of  a  diameter  greater  than  two  and  one-half  (23/0 
inches. 

NOTE:  Where  diameters  are  specified  in  connection  with  knots 
the  knot  shall  be  rated  on  the  basis  of  its  average  diam- 
eter. 

I  132] 


WOOD  POLES 


Sec.  2 


20.     SPECIFICATION  FOR  YELLOW  PINE  POLES* 

Quality  of  Timber.  All  poles  shall  be  cut  from  the  best  quality 
of  live,  straight  grained,  unbled,  long  leaf  yellow  pine.  The  butt 
end  shall  be  squared  and  the  top  end  pointed  to  an  angle  of  45 
degrees.  The  poles  shall  be  sawed  octagonal  in  shape  and  shall  be 
dressed,  with  the  heart  running  parallel  to  the  line  of  the  pole. 
The  timber  shall  be  free  of  decayed  or  loose  knots  or  clusters  of 
small  knots.  * 

Classification  and  Dimensions.  Poles  shall  be  classified  accord- 
ing to  their  butt  dimensions  into  two  classes,  to  be  known  as  Class 
"A"  poles  and  Class  "B"  poles,  with  dimensions  for  the  respective 
classes  as  specified  in  the  following  table.  Where  "top"  measure- 
ment is  specified  it  shall  be  the  diameter  at  the  top  of  the  pole 
and  where  "butt"  measurement  is  specified  it  shall  be  at  the  dia- 
meter of  the  butt  end  of  the  pole. 

Inspection  and  Rejection.  All  poles  shall  be  subject  to  inspection 
by  the  purchaser's  representative,  either  in  the  woods  where  the 
trees  are  felled,  or  at  any  point  of  shipment,  or  destination.  Each 
pole  thus  inspected  shall  be  marked  according  to  its  length  and  class 
with  a  marking  hammer,  by  the  purchaser's  representative.  All 
poles  failing  to  meet  these  specifications  shall  be  rejected. 


DIMENSIONS  OF  POLES  IN  INCHES  (DIAMETER) 

Length  of 
Poles. 
(Feet.) 

CLASSES. 

A 

B 

Top. 

Butt  End. 

Top. 

Butt  End. 

30 

8 

11 

7 

10 

35 

8 

12 

7 

11 

40 

8 

13 

7 

12 

45 

8 

14 

7 

12 

50 

8 

15 

7 

13 

55 

8 

16 

7 

14 

60 

8 

17 

65 

8 

18 

*  National  Electric  Light  Association  Specification. 

[  133  ] 


Sec.  2 


WOOD  POLES 


21.  SPECIFICATIONS  FOR  CREOSOTED  YELLOW 
PINE  POLES.* 

These  specifications  are  for  Class  A,  B  and  C  poles  of  Southern 
Yellow  Pine  treated  with  Dead  Oil  of  Coal  Tar. 

Quality  of  Poles.  All  poles  shall  be  sound  southern  yellow  pine 
(longleaf,  shortleaf,  or  loblolly  yellow  pine,)  squared  at  the  butt, 
reasonably  straight,  well  proportioned  from  butt  to  top,  peeled  and 
with  knots  trimmed  close.  All  pales  shall  be  free  from  large  or 
decayed  knots.  All  poles  shall  be  cut  from  live  timber. 

It  is  desired  that  all  poles  be  well  air  seasoned  before  treatment 
and  such  poles  shall  be  treated  in  accordance  with  the  requirements 
for  treating  seasoned  timber  contained  in  the  "Specifications  for 
Creosoting  Timber"  referred  to  in  Section  9.  The  poles  shall  not 
be  held  for  seasoning,  however,  up  to  the  point  where  local  experi- 
ence shows  that  sap-wood  decay  would  begin.  Unseasoned  poles 
shall  be  treated  in  accordance  with  the  requirements  for  treating 
unseasoned  timber  contained  in  the  above  mentioned  specifications. 

All  poles  shall  be  sufficiently  free  from  adhering  "inner  bark" 
before  treatment  to  permit  the  penetration  of  the  oil.  If  the  "inner 
bark"  is  not  satisfactorily  removed  when  the  pole  is  peeled,  the 
pole  shall  either  be  shaved,  or  be  allowed  to  season  until  the  "inner 
bark"  cracks  and  tends  to  peel  off  of  the  surface  of  the  pole. 

Dimensions.  The  dimensions  of  the  poles  shall  not  be  less  than 
those  given  in  the  following  table: 


DIMENSIONS  OF  POLES  IN  INCHES  (CIRCUMFERENCE). 

Class  A 

Class  B 

Class  C 

Length  of  Poles 

(Feet.) 

6'  from  Butt. 

6'  from  Butt. 

6'  from  Butt. 

25 

33 

30 

28H 

30 

35 

32 

3fli2 

35 

38 

34 

32 

40 

40 

36 

34 

45 

42H 

38 

36 

50 

44H 

40 

38 

55 

47 

42H 

40 

60 

49 

44^ 

42 

65 

51 

47 

44 

70 

53 

49 

46 

75 

55 

51 

80 

57 

No  class  A  poles  having  a  top  circumference  of  less  than  22  inches 
will  be  accepted. 


*  American  Telephone  &  Telegraph  Co.  Specification. 

[  134] 


CONCRETE  POLES  Sec.  2 

No  class  B  poles  having  a  top  circumference  of  less  than  20  inches 
will  be  accepted. 

No  class  C  poles  having  a  top  circumference  of  less  than  18  inches 
will  be  accepted. 

Framing  of  Poles.  Before  the  poles  are  subjected  to  the  creosoting 
process  they  shall  be  framed,  unless  otherwise  ordered,  in  the  fol- 
lowing manner  and  as  shown  in  drawing  No.  — . 

The  tops  of  all  poles  shall  be  roofed  at  an  angle  of  ninety  (90) 
degrees. 

All  class  A  poles  shall  have  eight  (8)  gains,  all  class  B  poles  shall 
have  four  (4)  gains  and  all  class  C  poles  shall  have  two  (2)  gains. 

The  gains  shall  be  located  on  the  side  of  the  pole  with  the  greatest 
curvature,  and  on  the  convex  side  of  the  curve.  The  faces  of  all 
gains  shall  be  parallel.  Each  gain  shall  be  four  and  one-half 
(4 J/0  inches  wide  and  one-half  (Yi)  inch  deep,  spaced  twenty-four 
(24)  inches  on  centers.  The  center  of  the  top  gain  shall  be  twelve 
(12)  inches  from  the  apex  of  the  gable.  A  twenty-one  thirty-second 
(f|)  inch  hole  shall  be  bored  through  the  pole  at  the  center  of  each 
gain  perpendicular  to  the  plane  of  the  gain. 

Inspection.  The  quantity  of  dead  oil  of  coal  tar  forced  into  the 
poles  shall  be  determined  by  tank  measurements,  and  by  observing 
the  depth  of  penetration  of  the  oil  into  the  pole.  In  the  case  of 
poles  having  a  growth  of  sapwood  not  less  than  one  and  one-half 
(1J/6)  inches  in  thickness,  the  depth  of  penetration  shall  be  not  less 
than  one  and  one-half  (1^2)  inches.  In  the  case  of  poles  having  a 
growth  of  sapwood  less  than  one  and  one-half  (1J^)  inches  in  thick- 
ness, the  dead  oil  or  coal  tar  shall  penetrate  through  the  sapwood 
and  into  the  heartwood. 

Depth  of  penetration  shall  be  determined  by  boring  the  pole 
with  a  one  (1)  inch  auger.  The  right  is  reserved  to  bore,  for  this 
purpose,  two  holes  at  random  about  the  circumference,  one  hole  (5) 
five  feet  from  the  butt  and  one  hole  ten  (10)  feet  from  the  top. 
After  inspection  each  bore  hole  shall  be  first  filled  with  hot  dead  oil 
of  coal  tar,  and  then  with  a  close  fitting  creosoted  wooden  plug. 

The  rejection  of  any  pole  on  the  score  of  insufficient  penetration 
shall  not  preclude  its  being  retreated  and  again  offered  for  in- 
spection. 

REINFORCED  CONCRETE  POLES. 

22.  General.  Reinforced  Concrete  poles  are  divided  into  two 
general  classes,  the  solid  and  the  hollow  type;  the  latter  type  serves 
a  two  fold  purpose  of  decreasing  the  weight  of  the  pole  and  providing 
a  means  for  making  connections  through  the  pole  from  aerial  lines 
to  underground  cable. 

The  solid  type  has  been  used  to  the  greatest  extent  in  the  United 
States,  the  probable  reason  being  that  this  type  is  more  easily  made. 

In  the  casting  of  concrete  poles  horizontal  forms  are  generally 
employed,  although  in  several  instances  poles  have  been  cast  in 
position  in  vertical  forms. 

The  forms  for  casting  poles  (the  types  of  which,  are  illustrated  in 

[  135  ] 


Sec.  2  CONCRETE  POLES 

Figs.  34  and  35),  generally  consist  of  tapered  troughs  of  wood  or 
steel  of  the  desired  form,  so  constructed  that  the  sides  can  be  removed 
after  the  concrete  has  set. 

The  general  requirements,  of  a  form  for  concrete  poles,  are  the 
same  as  for  any  other  kind  of  concrete  work  where  the  forms  are  to 
be  used  repeatedly. 

The  material  should  be  such  that  there  will  be  no  warping  and  the 
construction  should  be  such  that  there  will  be  no  leakage  when  using 
sloppy  concrete,  no  bulging  of  the  sides  when  filled,  and  that  it  will 
be  sufficiently  rigid  to  retain  its  shape  with  ordinary  handling. 

In  general,  a  square,  octagonal,  circular  or  other  cross-section 
may  be  used,  but  it  is  desirable  as  a  matter  of  appearance,  since 
sharp  corners  are  difficult  to  make  and  subject  to  accident,  that  all 
such  corners  be  chamfered  or  rounded.  The  minimum  diameter, 
or  width,  at  the  top  may  be  made  5  or  6  inches  for  small  poles,  and 
increased  as  required  for  the  strength  and  appearance  of  long  poles, 
or  poles  carrying  a  heavy  line.  In  any  case,  care  should  be  exercised, 
in  determining  the  taper  and  reinforcement,  that  no  weak  section 
occurs  at  some  distance  above  the  ground-level. 

23.  Steel  Reinforcing  (Fig.  36.)  When  steel  is  embedded  in  well- 
made  concrete  its  preservation  is  perfect,  and  the  life  of  a  reinforced 
monolith  is  practically  indefinite.  If  designed  and  built  with  the 
same  attention  now  given  other  materials,  reinforced  concrete  poles 
should  attain  the  necessary  strength  and  give  satisfactory  service. 

The  present  practice  differs  rather  widely  as  to  the  most  economical 
or  most  desirable  distribution  of  reinforcement.  It  is  now  generally 
conceded,  in  reinforced  concrete  work,  that  the  finer  the  distribu- 
tion of  metal,  the  greater  the  homogenity  and  strength  of  the  con- 
struction. However,  in  the  case  of  poles  where  the  concrete  is 
deposited  within  narrow  forms,  other  conditions  partly  modify  or 
control  the  distribution. 

In  construction,  such  as  concrete  poles  or  other  work,  in  which 
there  is  a  relatively  large  and  important  amount  of  reinforcing, 
great  care  must  be  exercised  to  thoroughly  tamp  or  puddle  the  con- 
crete as  it  is  deposited,  in  order  to  prevent  pockets,  and  to  insure 
every  lineal  inch  of  metal  having  a  firm  adherence  to  the  concrete. 
In  such  structures,  the  increase  in  stress  in  the  reinforcement  must 
be  very  rapid,  and  the  additions  of  stress  are  dependent  upon  the 
efficiency  of  the  connection  between  the  steel  and  the  concrete. 
Mechanical  bond  or  deformed  bars,  i.  e.  twisted  squares  or  bars  with 
various  projections  in  their  surfaces  are  superior  to  smooth  bars  for 
work  in  which  high  stresses  must  be  developed  in  short  lengths. 
Rods  may  often  be  bent  into  hooks  or  clamped  together  to  advantage. 

Reinforcing  metal  may  be  either  medium  grade  steel  with  an 
ultimate  strength  of  60,000  to  70,000  pounds  per  square  inch  and 
an  elastic  limit  of  30,000  to  40,000  pounds  per  square  inch  and  capable 
of  being  bent  cold  about  its  own  diameter,  or  it  may  be  high  carbon 
steel  with  an  ultimate  strength  of  80,000  to  100,000  pounds  per 
square  inch,  and  an  elastic  limit  of  40,000  to  60,000  pounds  per 

[  136] 


CONCRETE  POLES 


Sec.  2 


square  inch,  and  capable  of  being  bent  cold  about  a  radius  equal  to 
four  times  the  diameter  of  the  rod.  Since  the  elastic  limits  of  these 
two  grades  of  material  are  quite  different,  they  will  have  a  very 


marked  effect  upon  the  design  and  there  will  be  no  similarity 
between  two  poles  of  the  same  dimensions  and  reinforcement  in 
which  different  grade  rods  are  used.  Owing  to  the  fact  that  in  a 

[137] 


Sec.  2 


CONCRETE  POLES 


[  138] 


CONCRETE  POLES  Sec.  2 

pole  the  stresses  in  the  reinforcement  must  change  rapidly  in  amount 
with  every  lineal  foot  of  the  pole,  it  is  most  essential,  at  least  for 
high  strength  poles,  to  use  mechanical  bond  or  twisted  bars.  It  is 
also  necessary  to  provide  diagonal  or  spiral  reinforcing  when  poles 
are  to  be  subjected  to  torsion,  although  the  close  spacing  of  horizontal 
ties  will  be  of  assistance.  The  horizontal  ties  are  needed  primarily 
to  restrain  the  rods  from  local  buckling  with  consequent  spalling  off 
of  concrete.  The  rods  should  be  tied  to  the  horizontal  straps  or 
other  secondary  system  at  each  intersection,  in  order  to  assist  in 
developing  bond  stress.  In  view  of  the  character  of  service  to 


FIG.  36. — Steel  reinforcement  for  solid  concrete  pole  and  cross-arm. 

which  horizontal  bands  or  spacers  are  subjected,  the  use  of  cast 
rings  or  bands  is  inadvisable. 

24.  Concrete  Mixture.  The  most  commonly  used  mixture  is 
1:2:4  Portland  Cement,  sand,  and  broken  stone  or  gravel.  It 
should  be  mixed  wet,  using  carefully  selected  materials  and  tamped 
or  churned  to  eliminate  air-bubbles,  obtain  a  good  surface,  and 
thorough  contact  with  the  reinforcement.  Such  a  mixture  when 
well  made  has  an  average  compressive  strength  of  about  900  pounds 
per  square  inch  in  seven  days,  2400  pounds  per  square  inch  in  one 
month,  3100  pounds  pel  square  inch  in  three  months  and  4400  pounds 
per  square  inch  in  six  months.  If  conditions  make  it  desirable  to 

[  139  1 


Sec.  2  CONCRETE  POLES 

use  high  working  stresses,  a  month  or  more  should  elapse  before 
new  poles  undergo  severe  tests. 

25.  Molding  Pole.  The  bolt  holes  and  step  bolt  sockets  must  be 
cast  in  place  during  the  concreting.  Hardwood  blocks  may  be  used 
for  step  bolts,  although  a  cast  or  spiral  socket  is  preferable. 

No  attempt  should  be  made  to  remove  the  forms  until  the  concrete 
has  obtained  a  good  set,  and  care  must  be  exercised  to  prevent  injury 


FIG.  37. — Illustrating  flexibility  of  concrete  poles. 

to  the  surfaces  during  such  removal.  The  forms  should  be  kept 
covered  during  setting,  particularly  when  exposed  to  direct  sunlight 
in  hot  weather,  and  the  concrete  pole  should  be  well  sprinkled  and 
kept  under  canvass  for  some  days  after  the  forms  have  been  removed. 
A  freshly  made  concrete  pole  cannot  be  handled  or  rolled  with  im- 
punity until  it  has  become.well  set.  Further,  the  subsequent  han- 
dling, particularly  of  long  poles,  must  be  done  with  care,  and  is  pref- 

[  140  ] 


CONCRETE  POLES  Sec.  2 

erably  done  by  slings  attached  at  two  separate  points.  Plastering 
the  surface  of  poles  to  remove  pockets  or  to  produce  a  finished  surface 
is  particularly  objectionable.  The  former  should  be  avoided  by 
proper  workmanship,  and  the  latter  is  unnecessary  since  a  very  fine 
surface  can  readily  be  produced  by  rubbing. 

If  we  may  judge  by  the  kind  of  handling  which  concrete  poles 
successfully  withstand,  it  would  seem  entirely  probable  that  con- 
crete poles,  if  properly  reinforced,  will  survive  any  shocks  incident  to 
ordinary  service.  When  subjected  to  any  overload  or  accidental 
shock,  a  timber  pole  will  bend  and  in  some  cases  survive;  but 
failure,  when  it  does  occur,  is  usually  complete,  and  the  pole  falls. 


FIG.  38. — Hollow  concrete  poles  manufactured  by  the  Centrifugal  Process. 

Concrete  poles  on  the  contrary,  while  without  the  elasticity  of  timber, 
do  not  fall  by  breaking  off,  but  are  held  by  the  reinforcement  from 
falling  to  the  ground.  Tests  also  show  that  a  reasonable  amount 
of  bending  (sufficient  for  the  balancing  of  stresses  in  the  wires) 
can  occur  without  apparent  injury  to  the  pole.  (Fig.  37.) 

26.  Hollow  Concrete  Poles  have  been  used  quite  extensively  in 
Europe.  Their  manufacture  is  usually  a  machine  process,  there 
being  two  general  methods  employed. 

The  first  method  is  the  centrifugal.  (Fig.  38.)  This  process 
consists  in  manufacturing  poles  in  revolving  forms  by  centrifugal 
force.  A  wet  mixture  of  rich  concrete  is  placed  in  a  tubular 
form,  inside  which  the  reinforcement  metal  has  been  fastened, 
and  revolved  at  high  speed.  It  is  claimed  that  the  centrifugal 

[141] 


Sec.  2  CONCRETE  POLES 

action  forces  the  concrete  to  an  even  thickness  against  the  reinforce- 
ment, the  operation  taking  place  in  a  warm  room  and  occupying 
but  a  few  minutes.  These  hollow  poles  when  set  have  the  butts 
filled  with  stones  to  the  ground  line. 

In  the  second  method  an  interior  form  or  mandrel  is  used  instead 
of  an  exterior  shell  as  in  the  centrifugal  process,  and  after  fitting 
the  steel  reinforcement  on  this,  a  fairly  dry  mixture  of  concrete  is 
mechanically  plastered,  on  the  revolving  mandrel  in  a  narrow  con- 
tinuous belt,  by  means  of  a  combination  of  conveyor  and  wrapping 
of  canvas  under  tension,  wound  spirally  the  length  of  the  pole. 
It  is  claimed  that  both  this  and  the  centrifugal  process  have  given 
very  satisfactory  results  in  Europe. 


FIG.  39. — Hand-made  hollow  concrete  pole  (collapsible  core.) 

Hollow  concrete  poles  have  been  made  by  hand  in  this  country, 
in  which  the  core  is  made  collapsible  and  is  removed  as  soon  as 
the  concrete  has  set  sufficiently  to  bear  its  own  weight.  (Fig.  39.) 

Another  method  consists  in  molding  poles  in  forms  similar  to 
those  used  for  solid  poles.  When  the  mold  is  about  orie-third 
poured,  a  hollow,  conical  galvanized  iron  core  is  inserted  in  the 
mold  and  the  remainder  of  the  concrete  and  reinforcement  is  put 
in  place.  The  core  is  wrapped  loosely  with  a  spiral  of  building 
paper,  which  facilitates  the  removal  of  the  core  after  the  concrete 
has  set.  The  poles  are  constructed  in  a  horizontal  position  and 
reinforced  with  four,  six  and  eight  bars,  as  desired.  The  top  of 
the  mold  is  left  op?n  for  pouring  the  concrete  and  when  it  is  filled 
the  concrete  is  tamped  down  and  troweled  off  smooth. 

[142] 


CONCRETE  POLES 


Sec.  2 


[143] 


Sec.  2 


CONCRETE  POLES 


When  the  form  is  filled,  the  concrete  is  allowed  to  set  for  several 
hours;  the  core  is  then  partially  removed  and  the  pole  is  allowed  to 
set  from  twenty-four  to  forty-eight  hours  longer.  The  pole  is 
cured  by  wetting  it  thoroughly  each  day  for  twenty-five  to  thirty 
days. 

It  is  an  established  fact  that  satisfactory  concrete  poles  can  be 
made  and  are  now  in  service.  The  only  consideration  would  seem 


FIG.  43.— Steel  pole  30  feet  high. 

to  be  that  of  mechanical  efficiency  and  actual  cost.  The  question 
of  mechanical  efficiency  is  in  reality  combined  with  that  of  cost. 
Concrete  poles  have  been  built  at  a  low  original  cost,  but  with  an 
equally  low  mechanical  efficiency,  while  others  have  been  built  at 
excessive  cost  and  excessive  strength.  Neither  extreme  is  good 
engineering  or  good  economics.  The  successful  concrete  pole  must 
be  one  that  has  a  strength  at  least  comparable  with  a  Class  "A" 


STEEL  POLES 


Sec.  2 


wood  pole,  the  cost  of  which,  including  maintenance,  replacement, 
etc.  when  considered  for  a  term  of  years,  will  be  not  more  than  that 
of  an  equally  satisfactory  wood  pole. 


FIG.  44.— Double  circuit  three-phase  60,000  volt  steel  pole. 

27.  STEEL  POLES  AND  TOWERS 

Steel  poles  and  towers  may  be  divided  into  five  general  classes: 

(a)  Patented  Poles.  (Art.  28.) 

(b)  Tubular  Steel  Poles.  (Art,  29.) 

(c)  Latticed  Structural  Steel  Poles.  (Art,  30.) 

(d)  Structural  Steel  Towers.  (Art.  31.) 

(e)  Flexible  Frames.  (Art.  32.) 

[145] 


Sec.  2 


STEEL  POLES 


iii 


SSSS5 


05 


W»  M  CO  COM 


10 

W 
h-l 


tf 


m 


SSSsS 


•30£ 


[146] 


STEEL  POLES 


Sec.  2 


28.  Patented   Steel  Poles  are  manufactured  by  a  number  of 
companies  and  can  be  secured  in  various  heights.     The  design 
varies  considerably  out  the  manufacturers  of  such  poles  furnish 
data  on  their  strength,  from  which  data  calculations  can  be  made, 
enabling  the  computation  of  safe  working  loads. 

29.  Tubular  Steel  Poles  are  standardized  by  steel  tube  manu- 
facturers.    Their  use  is  confined  chiefly  to  trolley  construction  and 


FIG.  45. — Single  circuit  three-phase 
30,000  volt  steel  pole. 


FIG.  46.— Guyed  Bteel  pole,  13,200 
volts. 


to  supports  for  street  lighting  units.  Such  poles  are  made  of  two, 
three,  four  or  more  different  lengths  of  standard  or  special  steel 
tubing  of  various  sizes  and  it  is  advisable,  when  ordering  such  poles, 
to  confine  the  selection  to  standard  sections,  for  in  such  standard 
poles  the  length  of  the  various  sections  have  been  selected  so  that 
their  manufacture  results  in  a  minimum  waste  of  material. 


[1471 


Sec.  2 


STEEL  POLES 


Table  No.  5,  on  page  143,  has  been  compiled  from  data  pub- 
lished by  a  manufacturer  and  gives  the  extreme  weights  (light  and 
heavy)  and  the  respective  strength  of  standard  tubular  steel  poles 
of  the  two,  three  and  four  section  type  in  lengths  of  from  22  feet 
to  40  feet. 

30.  Structural  Steel  Poles  and  Towers  are  in  general  specially 
designed  for  the  particular  conditions  of  the  line  in  question. 


FIG.  47. — Double  circuft  three-phase 
steel  pole. 


FIG.  48. — Single  circuit  three-phase 
steel  pole. 


Their  design  is  so  diversified  and  is  dependent  on  such  a  variety 
of  conditions  that  the  subject  cannot  be  covered  in  detail,  also  such 
poles  are  usually  purchased  through  designing  engineers,  and,  there- 
fore, only  the  important  features  of  design  will  be  discussed. 

If  a  given  line  is  to  be  designed  in  a  logical  manner  and  with  a 
minimum  of  cut  and  try  methods,  an  assumption  of  the  various 

[148] 


STEEL  POLES 


Sec.  2 


loads  and  the  /desired  factors  of  safety  must  be  made.  Such  assump- 
tions will  enable  the  designer  to  mentally  predetermine,  to  some 
extent,  the  general  nature  of  the  supports,  or  at  least  to  narrow  the 
field  of  choice. 

These  assumptions  are  based  primarily  on  the  weight  of  the  con- 
ductor plus  the  assumed  ice  and  wind  load,  in  addition  to  which  it 


Fie».  49. — Double  circuit  narrow  base 

flexible  steel  frame  three-phase 

60,000  volts. 


FIG.  50. — Double  circuit  narrow 
base    flexible    steel   frame 
three-phase  44,000  volts. 


is  sometimes  specified  that  the  structure  must  care  for  one  or  more 
broken  wires  under  the  assumed  loaded  conditions. 

In  some  instances  the  test  loads  -which  sample  towers  or  poles 
must  withstand  are  specified.  Unfortunately  for  the  entire  success 
of  this  procedure  the  test  load  is  very  rarely  an  accurate  representa- 
tion of  the  possible  maximum,  nor  is  the  condition  of  the  test  struc- 
ture similar  to  that  of  many  of  the  structures  as  installed.  Test 

[149] 


Sec.  2 


STEEL  POLES 


loads  are  almost  always  applied  regularly  and  slowly;  and  in  many 
cases  uneccentrically.  The  test  structure  will  have  at  least  a  fairly 
good  foundation  and  be  composed  of  members  free  from  incipient 
bends  or  other  effects  of  mishandling.  It  would  also  be  very  well 
bolted  together  and  plumbed  with  greater  accuracy  than  the  average 
line  structure.  In  general,  it  may  be  said  that  an  expert  structural 


Fia.  51.— Single  circuit  three-phase 
steel  "A"  frame  60,000  volts.     ' 


FIG.  52.— Single  circuit  three-phase 
steel  "A"  frame  60,000  volts. 


assembler  should  be  able  to  obtain  test  loads  quite  noticeably  in 
excess  of  the  presumptive  average  strength  of  the  finally  erected 
structures. 

It  would  seem,  moreover,  that  the  period  of  usefulness  of  this 
practice  is  past,  and  that  competent  designers  should  be  able  to 
produce  structures  having  an  actual  strength  much  nearer  their 
predetermined  strength,  than  the  actual  loads  will  be  to  the  assumed 
loads. 

[150] 


STEEL  POLES 


Sec.  2 


The  failure  of  a  steel  pole  or  tower  will  almost  invariably  be  due 
to  the  buckling  of  a  main  compression  member  and  this  may  or  may 
not  be  superinduced  by  inefficient  bracing.  Owing  to  the  possible 
application  of  the  load  from  the  opposite  side  of  the  structure,  line 
supports  must  have  the  same  main  compression  section  at  each 
corner,  regardless  of  the  tension  stress.  The  compression  stress  per 


FIG.  53. — Double  circuit  three-phase 
steel  "A"  frame  35,000  volts. 

square  .inch  in  the  main  legs  is,  therefore,  the  first  and  most  im- 
portant determination.  A  secondary  condition  to  be  borne  in  mind 
during  the  foregoing  calculations  is  that  the  selected  section  must 
be  of  a  size  suitable  for  the  connection  of  the  desired  bracing. 

A  long  slender  member  is  not  well  adapted  to  take  compression 
and  it  has  been  customary  in  other  work  to  limit  the  relation  of 
the  length  to  the  radius  of  gyration.  In  transmission  line  construc- 

[  151] 


Sec.  2 


STEEL  POLES 


tion  very  much  higher  values  of  this  ratio  have  been  used  than  are 
generally  permitted  in  other  work.  It  is  probably  not  necessary  to 
adhere  to  the  low  limits  of  building  construction,  but  it  is  equally  prob- 
able that  in  some  cases  heretofore,  too  much  latitude  has  been  taken. 
Inasmuch  as  the  strength  of  the  main  leg  members  of  the  pole 


FIG.  54. — Double  circuit  three-phase  steel 
"A"  frames. 

or  tower,  as  well  as  most  of  the  bracing,  is  predicated  upon  their 
strength  as  compression  members,  the  most  important  requirement 
of  a  specification  next  to  the  broken  wire  condition,  is  the  formula 
for  compression  members  known  as  the  column  formula. 

Unfortunately,  the  many  column  formulae  in  existence  are  stated 
in  terms  of  safe  working  unit  stresses,  which  renders  them,  unless 

[152] 


STEEL  POLES 


Sec.  2 


\ 


[153] 


Sec.  2 


STEEL  POLES 


their  factor  of  safety  is  known,  almost  valueless  to  the  inexpert 
transmission  line  designer.  This  is  due  to  the  fact  that  in  general, 
in  transmission  line  construction,  it  is  the  ultimate  or  breaking 
strength  that  is  to  be  determined  in  order  that  a  specified  factor  of 
safety  may  be  applied  thereto. 
In  pole  and  tower  design,  the  compression  members  are  simple  in 


FIG.   56.  —  Single    circuit   three-phase 

steel  tower  50  feet  high  for 

66,000  volts. 


FIG.   57. — Double  circuit  three-phase 
steel  tower,  50  feet  high,  for 
66,000  volts. 


type,  usually  single  angles  with  relatively  large  ratios  of  the  un- 
supported length  to  the  radius  of  gyration  i.  e.  ;.  Failure  occurs 
when  such  members  buckle,  as  the  structure  becomes  distorted  and 
useless,  though  it  may  not  fall  to  the  ground.  It  is  readily  apparent 
that  any  incipient  bends  in  such  columns  will  very  markedly  affect 
the  theoretical  compressive  strength.  In  addition,  it  is  quite  pos- 
sible to  select  sections  such  as  4"  x  4"  x  J£"  angles,  or  example, 
whose  theoretical  strength  exceeds  their  actual  strength.  This  s 

[154] 


STEEL  POLES 


Sec.  2 


due  to  the  fact  that  in  such  large  thin  sections,  failure  may  start  by 
the  local  buckling  of  the  legs  of  the  angle. 

The  function  of  lacing  is  to  stiffen  the  connected  members  by 
reducing  the  unsupported  length  of  the  compression  section  and 
also  to  transmit  shearing  stresses.  If  the  shear  is  relatively  large, 
the  limiting  condition  may  be  the  number  of  rivets  connecting  the 


FIG.  5S. — Double  circuit  steel  corner 
tower,  40  feet  high. 


lattice  to  the  main  section,  otherwise  it  will  be  the  stiffness  of  the 
lattice  bar  itself;  that  is,  the  lattice  is  a  compression  member  whose 
strength  depends  upon  its  ratio  of  stiffness  or  7.  Since  the  minimum 
radius  of  gyration,  of  a  flat  section  or  bar  is  much  smaller  than  that 
of  an  angle,  the  unsupported  length  of  the  former  must  be  less. 
Again  flat  lacing  is  more  subject  to  accidental  injury  than  angle 
lacing  because  a  slight  bend  in  the  direction  of  the  thickness  may 

[155] 


Sec.  2  STEEL  POLES 

easily  occur  and  make  the  theoretical  compressive  strength  neg- 
ligible. 

When  double  lacing  is  used,  some  reduction  in  effective  length 
may  be  assumed  as  provided  by  the  connection  at  the  intersection. 
In  the  case  of  flat  lacing,  however,  it  is  not  proper  to  assume  the 


FIG.  59. — Double  circuit  steel  tower, 
40  feet  high. 

effective  length  as  the  distance  from  the  end  hole  to  the  intersection. 
Owing  to  the  larger  value  of  the  radius  of  gyration  of  an  angle  sec- 
tion, as  compared  with  a  flat  section,  the  former  allows  a  consider- 
able increase  in  the  width  of  the  main  members  with  less  material 
in  the  lacing.  Apart  from  the  avoidance  of  excessive  inclinations, 
the  available  angle  section  may  depend  upon  the  size  of  the  bolt 
needed  to  transmit  stress,  or  if  the  lacing  is  turned  in,  on  the  per- 
missible end  and  edge  distances. 

[  156  ] 


STEEL  POLES 


Sec.  2 


The  bracing  of  secondary  members,  if  they  are  not  liable  to 
accidental  injury  or  torsion,  may  properly  be  allowed  larger  ratios 
than  that  of  main  compression  members  which,  from  their  position, 
may  be  subject  to  both. 

The  horizontal  flanges  of  horizontal  or  inclined  angles  should 


FIG.  60. — Double  circuit  steel  corner  towers. 


always  be  turned  up,  as  this  position  drains  and  drys  quickly  and 
does  not  collect  dirt  or  hold  water.  Similar  reasoning  will  prohibit 
the  use  of  any  closed  pockets  or  semi-closed  pockets  anywhere  in 

[157] 


Sec.  2 


STEEL  POLES 


the  structure,  as  they  are  certain  to  become  clogged  with  refuse  and 
filled  with  water.  Since  moisture  is  a  necessary  condition  of  all 
decay  and  corrosion,  rapid  and  thorough  drainage  are  prime  req- 
uisites of  a  good  design  whether  the  material  be  timber  or  steel. 

One  bolt  connections  should  be  prohibited  in  the  main  bracing 
system  of  wide  base  towers,  except  possibly  for  the  connection  of 


FIG.  61. — Single  circuit  steel  anchor  tower  at  corner,  150,000  volts. 


such  secondary  members  as  sub-panel  struts,  whose  sole  function 
is  to  reduce  the  unsupported  length  of  another  member. 

Square  latticed  structural  steel  poles  may  be  of  any  width  from 
the  true  narrow  base  poles  used  along  curb  lines  to  the  wide  base 
poles  which  are  in  reality  towers.  There  is  no  fixed  dividing  line 

[158] 


STEEL  POLES  Sec.  2 

between  a  pole  and  a  tower,  unless  it  be  that  of  strength  and  rigidity, 
or  possibly  the  use  of  widths  which  preclude  shop  riveting  and  ship- 
ment assembled.  The  greater  number  of  the  structual  steel  poles 
used  are  square  in  cross-section,  one  angle  at  each  corner,  and  are 
assembled  and  riveted  before  shipment.  In  the  case  of  long  poles, 
it  will  frequently  be  found  advantageous  to  ship  in  two  sections  and 
bolt  them  together  in  the  field.  There  is  no  reasonable  objection 
to  the  use  of  such  field  bolts,  provided  a  splice  is  used  of  sufficient 
length  and  strength.  The  splice  angle  can  be  made  an  interior 
splice,  with  the  root  of  the  angle  ground  to  fit  the  fillet  of  the  main 
legs  and  thus  be  comparatively  unobstrusive  in  the  final  appearance 
of  the  pole. 

Several  types  of  poles  are  in  use,  the  most  common  being  those 
with  a  regular  taper  or  those  with  parallel  legs.  Parabolic  slopes 
have  been  used  and  they  present  a  very  graceful  appearance  under 
favorable  conditions,  although  the  rapid  increase  in  width  for  longer 
poles  may  result  in  an  inconvenient  spread  at  the  ground  line. 

The  design  of  square  latticed  poles  resolves  itself  into  a  determina- 
tion of  the  stresses  at  the  ground  line  or  rather  in  the  first  panel 
above  ground.  This  statement  is  based  upon  the  assumption  that 
owing  to  the  adoption  of  greater  top  widths  than  in  wood  poles, 
the  upper  portion  of  the  pole  has  an  excess  width  as  compared  with 
the  lowest  panel.  It  is  further  predicated  upon  there  being  no 
attempt  made  to  seriously  reduce  the  sections  of  the  material  in 
the  upper  half.  In  the  case  of  parabolic  slopes,  stress  determinations 
must  be  made  at  various  heights  since  the  widths  presumably 
follow,  more  or  less  closely,  the  changes  in  bending  moment  and  the 
weakest  section  may  be  anywhere. 

Owing  to  the  more  rigid  form  of  the  frame,  the  breaking  strength 
per  unit  of  area  in  a  pole  will  exceed  that  in  a  wide  base  tower. 
Again,  since  the  main  legs  have  little  inclination,  the  web  system  is 
compelled  to  carry  the  shearing  stresses,  which  in  a  tower  are  partly 
carried  by  the  main  legs.  For  these  reasons,  the  web  or  lattice  is 
more  often  limited  by  the  strength  required  than  in  the  bracing 
of  a  wide  tower.  The  shearing  stress  must,  therefore,  be  computed 
and  the  lattice  and  its  connection  to  the  main  legs  be  designed 
accordingly.  Single  flat  lacing  should  not  be  used  except  for  small 
stresses  and  in  narrow  widths,  since,  as  previously  stated,  its  strength 
is  low  and  it  is  subject  to  injury.  Double  flat  lacing  is  appliable  to 
greater  stresses  and  widths,  but  is  often  not  as  economical  as  angle 
lacing.  In  any  case  the  strength  of  the  pole  depends  upon  the  unit 
strength  of  the  weakest  unsupported  length,  which  is  usually  the 
lowest  panel,  but  may  be  the  entire  pole  if  the  width  is  small  and 
the  height  great.  That  is,  the  ^  of  the  entire  cross-section  of  the 
pole  may  be  greater  than  that  of  an  individual  panel.  The  char- 
acter and  spacing  of  the  lattice  will  determine  to  a  large  extent 
the  amount  of  support  afforded  by  it  to  the  main  leg  angles  at  the 
panel  joints. 

When  the  lacing  connects  to  both  faces  of  the  pole  at  the 

[159] 


Sec.  2 


STEEL  POLES 


elevation,  the  unsupported  length  of  main  leg  is  the  distance  between 
panel  joints.  If,  however,  the  lacing  is  staggered,  so  that  the 
support  is  in  one  direction  only  at  each  panel  point,  the  unsupported 
length  of  main  leg  is  somewhere  between  a  half  and  a  whole  panel 
length. 

31.  Flexible  Towers.     Assuming  that  a  reasonable  amount  of 
skill  has  been  employed  in  the  selection  of  spans,  heights  and  main 


FIG.  62. — Steel  tower  at  river  crossing. 


section,  the  most  important  provisions  for  an  adequate  A  frame 
line  are  the  installation  of  an  overhead  ground  wire  and  substantial 
foundations.  The  ground  wire,  which  should  be  of  considerable 
strength,  may  properly  be  given  a  little  less  sag  that  the  conductors, 
thus  acting  as  a  continuous  head  guy,  the  usefulness  of  which  can 
hardly  be  overestimated.  In  fact,  it  is  extremely  difficult  to  string 

[160] 


STEEL  POLES 


Sec.  2 


the  power  cables  unless  there  is  a  ground  wire  in  place  to  steady  the 
frame. 

The  conditions  which  promote  buckling  are  not  very  clearly 
understood,  or  rather  their  limits  are  not  definitely  known.  If  the 
main  channels  are  assumed  to  be  of  absolutely  identical  material 
and  the  base  of  the  foundation  is  firm  and  unyielding,  some  degree 


FIG.  63. — Double  circuit  three-phase 

steel  corner  tower,  50  feet  high,  for 

66,000  volts. 

of  difference  in  the  latteral  support  at  the  ground  line,  or  of  the 
rigidity  of  the  bracing  connections,  may  allow  sufficient  deflection 
to  start  the  buckling.  As  the  failure  is  a  compressive  failure  in  a 
relatively  long  column,  any  measures  which  restrain  such  a  column 
from  moving  sideways  at  any  point  will  be  of  effective  service. 
Thus  a  comparatively  long  stiff  connection  of  the  bracing  to  the 

6  [  161  ] 


Sec.  2 


STEEL  POLES 


main  legs  is  useful  as  it  stiffens  this  column  locally.  Such  connec- 
tions, therefore,  should  never  be  of  less  than  two  rivets  and  pref- 
erably of  not  less  than  6"  in  length.  Further,  the  diagonal  braces 
should  not  have  any  slack  and,  if  made  of  rods  or  adjustable  members, 
should  be  tightened  as  near  equally  as  possible. 


FIG.  64. — River  crossing  steel  tower, 
169  feet  high. 


The  present  tendency  is  toward  the  use  of  galvanized  ground  stub 
angles,  whether  the  superstructure  is  painted  or  galvanized  and 
with  either  concrete  or  earth  back  filling.  Galvanizing  such  mem- 
bers is  a  relatively  inexpensive  operation  and  they  can  be  painted 
over  the  galvanizing  at  the  ground  line.  No  reduction  of  section 
on  account  of  the  protective  coating  should  be  made  in  the  ground 
stubs. 

[162] 


STEEL  POLES 


Sec.  2 


Typical  structural  steel  poles,  towers  and  flexible  frames  are 
illustrated  in  Figs.  43  to  65. 

32.  Outdoor  Substations.  Outdoor  transformer  and  switching 
substations  vary  in  design  from  the  simple  transformer  supported 


FIG.  65.— Double  circuit  river  crossing,  three-phase,  66,000  volts,  2,000  feet  span 

on  wood  poles  to  the  more  complex  steel  structures  supporting 
switches  and  transformers  of  large  capacity.  A  number  of  types 
are  illustrated  in  Figs.  66  to  76. 

[163] 


Sec.  2 


SUB-STATIONS 


FIG.  66. — Outdoor  sub-station,  three-phase  3-2000  kv-a  transformers,  101,100 
volts  to  13,200  volts,  60  cycles. 


FIG.  67. — Outdoor  sub-station,   three-phase,    33,000  volts,    illustrating  air- 
break  switches  and  lightning  protection  devices. 

[  164] 


SUB-STATIONS 


Sec.  2 


FIG.  68.— Outdoor  sub-station,  three-phase,   150,000  volts  to  33,000  volts, 
60  cycles. 


FIG.  69. — Outdoor  sectionalizing  and  branch  tower,  three-phase,  66,000  volts. 


[165] 


Sec.  2 


SUB-STATIONS 


g  ™ 


SUB-STATIONS 


Sec.  2 


[167] 


Sec.  2 


SUB-STATIONS 


[  168  ] 


SUB-STATIONS 


Sec.  2 


FIG.  76. — Steel  outdoor  sub-station  for  33,000  volts.     1,  2  and  3  are  jib  cranes 
for  handling  transformers  A,  B,  and  C,  respectively. 


BIBLIOGRAPHY. 


United  States  Government  Reports. 

N.  E.  L.  A.  Publications. 

Electrical  World. 

Current  News,  Philadelphia  Electric  Company. 

American  Telephone  and  Telegraph  Company. 

Transmission  Line  Construction,  Lundquist. 

Publications  of  Various  Manufacturers. 

[169] 


SECTION  3 

CONDUCTORS  AND  WIRE  TABLES 


SECTION  3 
CONDUCTORS  AND  WIRE  TABLES 


TABLE  OF  CONTENTS 

Production  and  Refining  of  Conductor  Material 

Copper  ores  and  their  reduction 1 

Aluminum  ores  and  their  reduction 2 

Iron  and  steel  ores  and  their  reduction 3 

Copper  Clad  Wire 4 

Manufacture  of  Wire 

Working  Ingots 5 

Wire  Drawing 6 

Weatherproofing 7 

Rubber  Insulation 8 

Application  of  Rubber  Compound 9 

Vulcanizing 10 

Protection  of  Insulation 11 

Physical  Characteristics  12 

Tables  6  to  10  inclusive. 

Units  of  Resistance 13 

Table  11. 

Specific  Resistance 14 

Specific  Conductivity 15 

Percentage  Conductivity 16 

Matthiessen's  Standard  of  Conductivity 17 

Table  12. 

Specific  Resistance,  Relative  Resistance  and  Relative  Conduc- 
tivity of  Conductors, 18 

Table  13. 
Temperature  Coefticient 19 

Table  14. 

Table  15. 

Table  16. 

American  Steel  and  Wire  Gauge 20 

Brown  and  Sharpe  Gauge 21 

Birmingham  Gauge 22 

[173] 


Sec.  3  CONDUCTORS  AND  WIRE  TABLES 

ARTICLE 

Comparison  of  Wire  Gauges 23 

Table  17. 
Law  of  the  Brown  and  Sharpe  Gauge 24 

Table  18. 

Wire  Strands 25 

Table  19. 

Illustrations  of  Bare  Wire,  Strand  and  Cable 26 

Heating  Effects  of  Current 27 

Table  20. 

Table  21. 

Fig.  77. 

Table  22. 

Table  23. 

Table  24. 

Effective  Resistance 28 

Table  25. 

Figs.  78-81  inclusive. 

Explanation 

Guy  Wire 29 

Table  26. 
Extra  Galvanized  Special  Strands 30 

Table  27. 

Table  28. 

Copper,  Aluminum,  Copper  Clad  and  Iron  Wire  Tables 
Total  Pounds  Pull  Required  to  Break  Wire 

Solid  wire     Table  29. 
Stranded  wire     Table  30. 

Diameters  of  Wires,  Bare  and  T.B.W. 

Solid  wire    Table  31. 
Stranded  wire     Table  32. 

Weights  of  Wires,  Bare  and  T.B.W. 

Solid  wire     Table  33. 
Stranded  wire     Table  34. 

Resistance  of  Wires 

Solid  wire     Table  35. 
Stranded  wire     Table  36. 

Self-inductance 

Solid  wire     Table  37. 
Stranded  wire     Table  38. 

[174] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 

Capacity  ARTICLE 

Solid  wire    Table  39. 
Stranded  wire    Table  40. 

Inductive  Reactance 

Solid  wire,  25  cycles  Table  41. 

Solid  wire,  60  cycles  Table  42. 

Solid  wire,  100  cycles  Table  43. 

Stranded  wire,  25  cycles  Table  44. 

Stranded  wire,  60  cycles  Table  45. 

Stranded  wire,  100  cycles  Table  46. 

Charging  Current 

Solid  wire,    25  cycles  Table  47. 

Solid  wire,    60  cycles  Table  48. 

Solid  wire,  100  cycles  Table  49. 

Stranded  wire,  25  cycles  Table  50. 

Stranded  wire,  60  cycles  Table  51. 

Stranded  wire,  100  cycles  Table  52. 

Stranded  Aluminum  Wire  Equal  in  Conductivity  to  Copper 

Table  53. 
Correction  for  Internal  Inductance  of  Copper  Clad  Wire 31 

Figs.  84-87  inclusive. 
Average  Track  Resistance 

Table  54. 
Specifications 

Specifications  for  Galvanized  Steel  Strand 32 

Specifications   for   Copper   Wire   and   Cables   with 
Weather  Proof  Insulation 33 

Specifications  for  Bare  Hard  Drawn  Copper  Wire  and 
Strand 34 

Specifications  for  Hard  Drawn  Copper  Clad  Steel 
Wire 35 

Specifications    for   Aluminum    Wires    and    Cables, 
Weatherproof  Insulation 36 

Specifications  for  Bare  Aluminum  Wire 37 

Specifications    for    Rubber    Insulated    Tree    Wire 
Braided 38 

Specifications  for  Circular  Loom  Covered  Tree  Wire . .  39 


[175] 


CONDUCTORS  AND  WIRE  TABLES 

In  the  section  following,  data  are  compiled  on  conductors  and 
conductor  material,  in  which  some  general  information  is  given  on 
the  production  and  refining  of  the  conductor  material  and  also  a 
brief  description  of  wire  drawing  and  insulating. 

These  data  have  been  collected  with  the  cooperation  of  various 
wire  manufacturers.  A  comparison  of  the  diameters,  weights, 
strengths,  etc.,  of  the  various  sizes  of  wire,  as  produced  by  different 
manufacturers,  indicated  certain  discrepancies  and  therefore,  it  was 
necessary  to  confine  the  data  on  any  particular  wire  material  to 
that  furnished  by  one  manufacturer.  These  discrepancies  were 
slight,  however,  and  the  tables  given  herein  will  be  found  sufficiently 
accurate  to  apply  to  any  standard  product  which  may  be  purchased. 
The  tables  have  been  compiled  in  a  form  thought  to  be  most  con- 
ducive to  rapid  calculation  and  contain  only  such  wire  sizes  as  are 
considered  standard. 


PRODUCTION  AND  REFINING  OF  CONDUCTOR  MATERIALS 

1.  Copper.  Copper  ores  occur  in  many  and  various  forms  in 
widely  distributed  localities.  In  the  United  States  there  are  three 
localities  in  which  the  copper  mineralization  is  of  considerable  magni- 
tude. Approximately  95  percent  of  the  total  copper  ore  of  the 
country  is  mined  in  the  Lake  Superior,  Rocky  and  Sierra  Nevada 
Mountain  regions. 

The  copper  bearing  rocks  in  the  Lake  district  are  very  distinctly 
stratified  beds  of  trap,  sandstone  and  conglomerates  which  rise  at 
an  angle  of  about  45  degrees  from  the  horizontal  sandstone  which 
forms  the  basin  of  Lake  Superior.  One  peninsula  extending  into 
the  Lake  has  developed  copper  in  profitable  amounts,  almost  chem- 
ically pure. 

The  amount  of  copper  in  the  ore  as  mined  averages  about  3  per- 
cent, the  balance  being  rock,  which  is  intimately  mixed  with  the 
metal.  The  ore  is  first  subjected  to  a  mechanical  process  whereby 
the  metal  is  concentrated  into  a  small  bulk  and  the  rock  rejected. 
"Lake"  copper  is  so  pure  that  final  melting  without  refining  is 
practicable. 

The  deposits  in  the  Rocky  Mountains  and  in  the  Sierra  Nevadas 
show  all  phases  of  formation  from  the  original  unaltered  sulphide 
deposits  to  the  most  highly  altered  oxides  and  carbonates. 

A  Sulphide  ore  is  an  ore  in  which  copper  appears  in  chemical 
combination  with  sulphur  and  in  some  cases  is  first  roasted  or 
heated  so  that  the  sulphur  is  burned  off,  leaving  the  copper  and  iron, 
which  is  usually  present,  in  an  oxidized  or  burned  form.  In  another 
process  the  raw  unroasted  ore  is  thrown  into  a  furnace,  the  sulphur 
itself  burned  and  made  to  smelt  the  mass,  producing,  on  account  of 
its  chemical  nature,  a  highly  impure,  yet  very  valuable,  compound 

[177] 


Sec.  3  CONDUCTORS  AND  WIRE  TABLES 

with  iron  and  sulphur,  called  matte.  This  matte,  which  is  about 
half  copper,  is  poured  from  the  furnace  into  a  converter  and  the  iron 
and  sulphur  are  burned  out,  by  blowing  through  great  volumes  of 
air.  The  result  of  this  operation  is  blister  copper,  so  called,  on  ac- 
count of  the  blistered  appearance  of  the  surface  caused  by  the 
quantities  of  gases  absorbed  by  the  metal. 

If  copper  ore  occurs  in  an  oxidized  or  carbonate  form,  or  roasted 
ore  is  used,  a  blast  furnace  is  also  utilized  for  the  reduction.  Oxi- 
dized or  sulphide  ores  are  also  often  mixed  and  the  matte  is  blown. 

Blister  copper  contains  about  99  percent  of  copper,  which  is  not, 
however,  pure  enough  for  use  as  a  conductor  material.  If  a  suffi- 
cient amount  of  precious  metal  is  contained  in  it,  the  electrolytic 
refining  process  is  used,  by  which  method  the  blister  copper  is  dis- 
solved and  the  chemically  pure  copper  separated  from  the  impurities 
and  other  metals. 

The  blister  copper  or  electrolytic  copper  is  then  charged  iAto  a 
refining  furnace  and  melted  by  means  of  a  very  pure  fuel.  The 
furnace  is  a  simple  bowl  shaped  hearth,  covered  and  provided  with 
doors  for  skimming  and  stirring.  After  the  metal  is  quickly  melted 
and  the  last  traces  of  sulphur  have  been  removed  by  combination 
with  the  oxygen  from  the  flame,  the  process  known  as  rabbling  or 
flapping  is  begun.  This  is  a  violent  agitation  of  the  metal  through 
one  of  the  side  doors,  by  means  of  small  rabbles  or  pokers.  During 
the  flapping,  samples  are  frequently  taken  in  a  hemispherical  mould 
about  an  inch  in  diameter.  When  the  set  or  appearance  of  the 
solidified  metal  in  this  mould  indicates  that  sufficient  work  has  been 
done  upon  it,  the  surplus  oxygen  is  removed  in  order  to  prevent 
extreme  brittleness  and  the  lack  of  conductivity  incident  to  an  over- 
oxidized  metal.  This  is  done  by  poling  the  bath.  A  large  stick  of 
green  hardwood  is  introduced  into  the  bath,  which  burns  and  the 
metal  is  violently  agitated  by  the  gas  driven  off.  The  surface  of 
the  bath  is  covered  with  charcoal  to  prevent  further  oxidation,  and 
samples  are  very  frequently  taken.  This  is  continued  until  the  test 
piece  shows  tough  pitch  or  the  removal  of  the  excess  of  oxygen,  and 
that  the  metal  is  in  its  toughest  condition.  This  tough  pitch  con- 
dition is  essential  for  the  requirements  of  rolling  and  wire  drawing, 
as  copper  in  this  state  possesses  the  highest  degree  of  conductivity 
and  is  of  an  extremely  tough  and  ductile  nature.  The  metal  is  then 
poured  into  ingot-moulds  or  wire  bars,  in  which  form  it  goes  to  the 
wire  manufacturer. 

2.  Aluminum.  Although  aluminum  is  a  component  part  of  a 
very  large  portion  of  the  earth's  crust,  forming  an  essential  part  of 
all  granites,  gneisses,  clays  and  other  very  numerous  and  complex 
silicates,  there  are  very  few  natural  compounds  of  aluminum  which 
are  suitable  for  use  as  ores  for  the  production  of  the  pure  metal. 

The  only  compound  at  present  used,  from  which  aluminum  is  pro- 
duced, is  bauxite,  which  is  hydrated  aluminum  oxide  with  oxides  of 
iron,  silicon  and  titanium  as  impurities.  Ordinary  clays  are  so  high 
in  silicon  that  the  separation  of  the  aluminum  from  the  silicon  is 

[178] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 

extremely  difficult.  More  or  less  extensive  deposits  of  bauxite  are 
found  in  Arkansas,  Georgia,  France,  Ireland  and  in  a  few  other 
places. 

Before  bauxite  can  be  subjected  to  the  smelting  process,  it  must 
be  refined  and  purified  to  remove  from  it  the  last  possible  trace  of 
silicon,  iron  and  titanium,  water  and  other  impurities,  which  may 
be  present  in  it  as  mined.  Since  there  is  no  method  available  for 
the  further  purification  of  aluminum  when  once  it  has  been  obtained 
in  the  metallic  state,  its  purity  depends  almost  entirely  upon  the 
purity  of  the  ore  used.  The  bauxite  is  .therefore  put  through  an 
elaborate  chemical  process,  as  a  result  of  which  it  is  delivered  to  the 
ore  reduction  plants  in  the  form  of  practically  chemically  pure 
aluminum  oxide,  or  alumina. 

This  pure  alumina  is  then  subjected  to  the  smelting  or  reduction 
process,  which  is  purely  electrochemical  in  its  nature.  This  is 
carried  on  in  large  rectangular  iron  tanks  or  pots,  which  are  thickly 
lined  with  carbon  which  also  serves  as  one  electrode  for  the  very 
heavy  electric  current  required.  The  other  electrode  consists  of  a 
group  of  cylindrical  carbons  suspended  above  and  serving  to  lead 
the  current  into  the  tank  or  pot. 

The  details  of  the  reduction  process  vary  slightly  at  different 
plants,  but  fundamentally  the  processes  are  all  the  same  and  con- 
sist of  the  electrolytic  decomposition  of  alumina.  The  alumina  so 
electrolysed  is  first  dissolved  in  a  flux  or  fused  bath  of  a  suitable 
aluminum  salt,  which  is  maintained  in  a  molten  condition  by  the 
joulean  heat  of  the  current  passing  through  the  pot.  The  alumina 
(aluminum  oxide)  thus  carried  in  solution  is  broken  up  into  metallic 
aluminum  and  oxygen.  The  metallic  aluminum,  which  collects  at 
the  bottom  of  the  pots,  is  tapped  off  at  stated  intervals  and  the 
oxygen  combines  with  the  carbon  electrode  forming  carbon  dioxide. 

In  order  to  produce  aluminum  of  a  purity  sufficient  for  electrical 
conductor  purposes,  only  the  purest  ore  can  be  used  and  at  all  stages 
of  the  process  great  care  must  be  exercised  to  avoid  the  introduction 
of  impurities  into  the  metal. 

The  extra  pure  metal  so  obtained,  after  being  analyzed  and 
classified  according  to  purity,  is  sent  to  the  smelting  furnaces,  where 
it  is  carefully  melted  in  large  open  hearth  furnaces  and  cast  into  wire 
bars,  in  which  form  it  goes  to  the  wire  manufacturer. 

3.  Iron  and  Steel.  The  distribution  of  iron  ores  follows  in  a  gen- 
eral way  those  of  copper  statistics  showing  that  the  states  of  Michi- 
gan, Wisconsin  and  Minnesota  produce  about  80  percent  of  the  total 
ore  mined  in  the  United  States. 

The  southern  states,  Alabama,  the  Virginias,  Tennessee,  Ken- 
tucky, Georgia,  Maryland  and  North  Carolina  contribute  about  12 
percent  of  the  country's  supply.  The  balance  is  distributed  quite 
widely  along  the  Atlantic  Coast  range,  the  Mississippi  Valley  and 
Rocky  Mountains. 

Practically  all  of  the  ores  commercially  utilized  are  in  an  oxide  or 
carbonate  combination  so  that  a  simple  heating  to  the  reducing 

[  179  ] 


Sec.  3  CONDUCTORS  AND  WIRE  TABLES 

point  of  the  ore  in  contact  with  a  proper  reducing  material  is  sufficient 
to  bring  about  the  first  step  in  the  process. 

The  ore,  as  mined,  consists  of  two  main  constituents,  the  valuable 
material  which  contains  the  iron  and  quantities  of  rock  and  other 
materials  from  which  the  metallic  part  must  be  separated.  The 
ore  is  charged,  as  a  whole,  into  the  furnace  and  the  proper  mixing 
with  non-metallic  substances  relied  upon  to  form  the  final  products 
which  are  easily  fusible,  and  from  which  the  liquid  iron  will  separate 
itself  by  reason  of  its  greater  specific  gravity.  The  flux  as  these 
additions  are  called,  is  usually  limestone,  as  the  gangue  is  usually 
of  a  silicious  nature. 

The  ore,  fuel,  and  fluxes  are  charged  into  a  blast  furnace,  which 
is  a  cylindrical  stack  80  to  100  feet  high  and  about  20  feet  in  diameter 
at  its  largest  point,  having  suitable  arrangements  near  its  base  for 
blowing  in  great  volumes  of  air.  The  fuel  used  is  coke,  which  heats 
the  charge  to  its  melting  point  and  at  the  same  time  frees  the  iron 
from  its  chemical  bonds  in  the  ore.  The  earthy  portions  of  the  ore 
unite  with  the  limestone,  forming  a  waste  product  known  as  slag. 
The  carbon  in  the  coke  combines  with  the  oxygen  in  the  oxide  of 
iron,  thus  separating  the  metallic  iron  from  the  ore. 

The  metal  from  these  furnaces  is  called  Pig  Iron  and  is  employed 
mainly  in  this  shape  as  a  stepping  stone  toward  other  products. 

Pig  Iron  is  coarse-grained,  brittle  and  full  of  impurities,  which 
must  be  removed.  This  is  done  by  several  processes  in  one  of  which 
the  pig  is  mixed  with  steel  scrap  of  a  highly  selected  grade  and  the 
molten  mass  subjected  for  several  hours  to  the  purifying  action  of 
an  intensely  hot  flame,  by  which  the  various  impurities  are  elimi- 
nated. The  metal  is  then  poured  into  iron  moulds,  which  shape  it 
into  ingots.  The  ingots  are  taken  out  of  the  moulds  as  soon  as  the 
outside  has  firmly  solidified  and  are  plunged  in  a  deep,  white  hot  pit, 
where  they  are  kept  until  their  temperature  is  uniform  throughout. 
After  this  they  are  sent  to  the  wire  manufacturer. 

4.  Copper  Clad.  Copper  clad  wire  is  composed  of  a  steel  core 
around  which  is  formed  a  copper  sheath,  varying  in  thickness  in 
accordance  with  the  grade  of  wire,  which  sheath  is  practically 
welded  to  the  steel  core. 

In  one  process  of  the  manufacture  of  such  wire,  a  steel  billet,  of  a 
suitable  composition  for  wire  making,  is  carefully  pickled  and  washed, 
then  heated  to  a  given  temperature  and  lowered  into  a  furnace  con- 
taining molten  copper,  at  a  very  high  temperature,  where  it  is 
allowed  to  remain  until  an  alloy  forms  on  the  billet's  surface.  The 
billet  is  then  inserted  in  a  mould  of  such  a  diameter  that  a  space 
remains  around  the  billet  into  which  space  chemically  pure  molten 
copper  is  poured.  This  is  allowed  to  set;  the  billet  is  then  rolled 
to  wire  rod  which  is  put  through  the  ordinary  process  of  wire  draw- 
In  another  process  there  is  first  formed  a  two-metal  or  composite 
ingot  by  inserting  a  bar  of  high  grade  steel  of  suitable  length  and 
uniform  cross  section  into  and  in  close  contact  with  a  seamless 

[  180  ] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 

copper  tube  of  high  conductivity  and  physical  qualities,  and  of  equal 
length  and  exactly  finished  thickness, — the  diameter  of  the  core  and 
thickness  of  the  copper  being  accurately  predetermined  in  order  to 
give  the  proper  proportion  of  each  metal  in  the  finished  product. 
The  two-metal  ingot  thus  formed  is  then  placed  in  a  heating  furnace 
and  there  brought  to  a  temperature  suitable  for  welding.  While 
still  hot,  and  with  both  copper  and  steel  in  a  plastic  or  pasty  condi- 
tion, they  are  taken  to  the  rolls  and  there  the  two  metals  are  welded 
together. 

MANUFACTURE  OF  WIRE 

5.  Working  Ingots.    The  treatment  of  copper,  aluminum,  copper 
clad  or  steel  is  practically  the  same.     The  material  is  received  in 
approximately  the  same  size  and  length,  is  heated  and  then  passed 
through  a  rolling  mill,  reducing  the  size  and  finally  producing  a  rod 
which  may  be  a  quarter  of  an  inch  in  diameter  and  nearly  a  quarter 
of  a  mile  in  length. 

Up  to  this  point  the  metal  has  been  handled  hot,  but  during  the 
processes  of  wire  drawing  it  is  worked  in  the  cold  state. 

6.  Wire  Drawing  consists  briefly  in  pulling  the  wire  through 
tapering  holes  in  iron  or  steel  plates,  reducing  its  diameter  and  in- 
creasing its  length  with  each  draft  until  the  wire  has  undergone  a 
sufficient  number  of  drafts  and  consequent  reductions  to  bring  it 
to  the  proper  diameter. 

When  the  finer  sizes  of  wire  are  to  be  produced,  the  total  reduction 
cannot  be  made  in  one  series  of  drafts,  as  the  wire  must  be  treated 
at  intervals  to  relieve  the  strains  produced  by  the  cold  working. 
This  treatment,  called  annealing,  consists  in  heating  the  metal 
uniformly  to  a  sufficiently  high  temperature  to  remove  the  internal 
molecular  strains  and  to  make  the  metal  once  more  soft  and  ductile. 
This  may  be  repeated  many  times  before  the  necessary  amount  of 
reduction  has  been  attained.  The  finest  sizes  of  magnet  wire  are 
produced  by  drawing  through  holes  drilled  in  diamonds. 

7.  Weatherproof    Insulation.     In    the    manufacture    of    triple 
braided  weatherproof  wire,  the  wires  are  covered  by  three  closely 
and  evenly  woven  braids  of  strong  fibrous  material  after  which  they 
are  placed  in  a  hot  bath  of  weatherproof  insulating  compound.   They 
remain  in  this  bath  until  the  fibrous  insulation  is  completely  and 
thoroughly  saturated.     After  thoroughly  drying,  the  wire  receives 
a  dressing  of  mineral  wax  and  the  surface  is  then  thoroughly  finished 
and  polished. 

8.  Rubber  Insulation.     There  are  various  grades  of  crude  rubber 
usually  known  under  the  name  of  the  country  or  seaport  from  which 
they  come,  such  as  "Para,"  "Ceylon,"  etc. 

Rubber  for  insulation  purposes  must  be  free  from  impurities,  such 
as  bark  and  sand.  This  cleansing  is  done  by  passing  the  crude 
rubber  several  times  between  corrugated  steel  rolls,  revolving  at 
different  speeds  and  under  a  constant  stream  of  water.  Thus  the 

[181] 


Sec.  3  CONDUCTORS  AND  WIRE  TABLES 

rubber  is  washed  and  cleansed  from  such  impurities  and  is  delivered 
in  a  sheet  ready  to  be  dried.  Crude  rubber  is  affected  by  changes 
in  temperature,  hardening  with  cold  and  softening  and  losing  its 
shape  with  heat.  In  such  an  uncured  state  it  readily  oxidizes  and 
is  particularly  susceptible  to  the  action  of  certain  solvents.  To 
obtain  the  properties  needed  in  the  insulation  of  a  wire,  the  rubber 
must  be  compounded  with  other  materials  and  then  vulcanized. 

Compounding  consists  of  mixing  the  rubber  with  other  substances, 
chiefly  powdered  minerals,  including  a  small  percentage  of  sulphur. 
After  the  rubber  has  been  warmed  to  a  plastic  condition  in  the 
heated  mixing  rolls,  which  are  smooth  and  run  at  different  speeds, 
the  compounding  ingredients  are  added  to  the  rubber  and  the  whole 
is  thoroughly  kneaded  together  by  the  action  of  the  mixing  rolls, 
until  the  resulting  compound  is  homogeneous  in  nature  and  of  suit- 
able physical  condition. 

9.  Application  of  the  Rubber  Compound.     Two  different  methods 
are  commonly  in  use  for  applying  rubber  insulation  to  wires.     In 
one,  a  machine  similar  in  action  to  a  lead  press  is  used.     The  rubber 
is  forced  by  a  revolving  worm  into  a  closed  chamber  at  high  pressure, 
at  the  same  time  being  heated  to  a  soft  and  plastic  state  by  a  steam 
jacket.     The  wire  enters  this  same  chamber  through  a  nozzle  of  its 
own  diameter,  and  leaves  it  from  a  nozzle  having  the  diameter  of 
the  intended  insulation.     The  wire  thus  comes  out  with  a  seamless 
coating  of  rubber  insulation. 

In  the  other  method  of  application,  the  rubber  is  sheeted  on  a 
calender  having  heavy  smooth  rolls  and  the  sheets  thus  made  are 
cut  into  narrow  strips,  the  width  and  thickness  of  which  depends 
upon  the  size  of  the  wire  to  be  insulated  and  the  number  of  covers 
to  be  used.  In  this  method  the  wire  is  passed  between  one  or  more 
pairs  of  grooved  rolls  running  tangent  to  each  other.  As  the  wire 
enters  each  pair  of  rolls,  one  or  more  strips  of  rubber  enter  at  the 
same  time  and  the  grooves  fold  a  uniform  thickness  of  rubber  about 
the  wire,  the  edges  meeting  in  a  continuous  seam.  All  surplus 
rubber  is  cut  off  by  the  rolls  at  the  seams.  These  seams  being  made 
between  two  pieces  of  the  same  unvulcanized  cohesive  stock  under 
very  great  pressure,  become  invisible  in  the  finished  wire  and  can 
be  determined  only  by  a  ridge  along  the  insulation. 

In  the  process  of  vulcanizing,  the  rubber  at  the  seams  is  kneaded 
together  so  that  the  insulation  at  this  point  is  as  dense  and  homo- 
geneous as  at  any  other  part  of  the  insulation. 

10.  Vulcanizing.    To    vulcanize    rubber    compounds    they    are 
subjected  to  temperatures  somewhat  above  the  melting  point  of 
sulphur,  which  temperatures  are  usually  obtained  by  use  of  steam 
under  pressure.     This  operation  causes  the  sulphur  in  the  compound 
to  unite  chemically  with  the  rubber  and  other  ingredients  of  the 
compound,  with  the  results  that  the  rubber  is  no  longer  plastic, 
but  becomes  firm,  elastic,  strong,  less  susceptible  to  heat  and  cold, 
to  the  action  of  the  air  and  less  readily  affected  at  ordinary  tempera- 
tures, by  the  usual  solvents  of  unvulcanized  rubber.     Its  chemical 

[  182  ] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 

and  mechanical  properties  depend  considerably  on  the  time  and  the 
temperature  of  vulcanization  and  on  the  amount  of  sulphur  used. 

11.  Protection    of    Rubber    Insulation.     Rubber    insulation    for 
aerial  work  should  be  protected  by  a  winding  of  tape,  or  by  a  braid, 
or  a  tape  and  one  or  more  braids.     The  tape  used  consists  of  a  good 
grade  of  cloth  filled  with  a  high  class  rubber  compound.     The 
braiding  consists  of  a  strong  cotton  yarn,  knitted  tightly  and  evenly 
about  the  insulation  by  a  machine  resembling  a  stocking  machine. 

The  braid  is  then  saturated  with  a  black  weatherproof  compound, 
which  is  waxed  and  polished. 

12.  PHYSICAL    CHARACTERISTICS.     The   average    physical 
characteristics  of  copper,  aluminum,  copper  clad,  steel  and  iron  wire 
are  given  in  Tables  6  to  10  inclusive.     While  copper  clad  is  a  com- 
pound wire  consisting  of  copper  and  steel,  it  will  be  noted  that  its 
characteristics  differ  from  both  those  of  copper  and  steel. 

The  physical  characteristics  of  compound  stranded  cables,  such 
as  copper  steel  core  and  aluminum  steel  core  cables  have  not  been 
included,  since  the  relative  proportions  of  the  compounding  vary  to 
such  an  extent  with  the  mechanical  and  electrical  conditions  to  be 
obtained  by  such  compounding,  that  such  cables  are  practically  a 
special  product. 


[  183  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


TABLE  6 
COPPER  WIRE 
Physical  constants  of  commercial  wire.     Average  values 

Annealed 

Hard 

Percent  Conductivity  (Matthiessen's  Standard  100) 
Specific  Gravity  

99-102 
8.89 
.320 
.003027 
28,000 
32-34,000 
12,000,000 
.0000171 
.0000095 
1100° 
2012° 
176 

8.7 

1.594 
.6276 
9.59 
10.36 
50,600 

96-99 
8.94 
.322 
.003049 
30-35,000 
50-67,000 
16,000,000 
.0000171 
.0000095 
1100° 
2012° 
176 

8.7 

1.626 
.6401 
9.78 
10.57 
51,600 

Pounds  in  1  cubic  inch    

Pounds  per  1000  ft  per  circular  mil 

Elastic  Limit  in  Ibs 

Ibs. 
Ultimate  Strength  ' 

Modulus  of  elasticity  •  —  ^  =~~ 

y  m.Xsq.  in.  ' 
Coefficient  of  Linear  Expansion  per  °  C  

Coefficient  of  Linear  Expansion  per  °  F 

Melting  Point  in  °  C 

Melting  Point  in  °  F  

Specific  Heat  (watt-seconds  to  heat  1  Ib.  1°  C.)  
Thermal     Conductivity     (watts    through    cu.    in., 

Resistance: 
Michroms  per  centimeter  cube  0°  C  

Microhms  per  inch  cube  0°  C  

Ohms  per  mil-foot  0°  C 

Ohms  per  mil-foot  20°  C 

Cir.  Mils 
54,600 

Cir.  Mils 
55,700 

Pounds  per  mile  ohm  0°  C.           

Cir.  Mils 
810 
875 
.0042 
.00233 

Cir.  Mils 
830 
896 
.0042 
.00233 

Pounds  per  mile  ohm  20°  C.                                 ... 

Temperature  Coefficient  per  °  F  

L184] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


TABLE  7 

ALUMINUM  WIRE 

Physical  constants  of  commercial  wire.     Average  values 


Aluminum 
Wire 


Percent  Conductivity  (Matthiessen's  Standard  100) 61 

Specific  Gravity 2.68 

Pounds  in  1  cubic  inch .0967 

Pounds  per  1000  ft.  per  circular  mil .000920 

Elastic  Limit 14000-16000 

Ibs 

Ultimate  Strength  - — ^ 23000-27000 

Ib.  Xin. 

Modulus  of  elasticity  -n  Xg — ^ 9,000,000 

Coefficient  of  Linear  Expansion  per  °  C .0000231 

Coefficient  of  Linear  Expansion  per  °  F .0000128 

Melting  Point  in  °  C 657° 

Melting  Point  in  °  F 1215° 

Specific  Heat  (watt-seconds  to  heat  1  Ib.  1°  C.) 412 

Thermal  Conductivity  (watts  through  cu.  in.,  temperature 

gradient  1°  C.  at  100°  C.) 3.85 

Resistance: 

Microhms  per  centimeter  cube  0°  C 2.612 

Microhms  per  inch  cube  0°  C 1.028 

Ohms  per  mil-foot  0°  C 15.72 

Ohms  per  mil-foot  20°  C 16.97 

AAACA 

Resistance  per  mile  0°  C 

Cir.  Mils 

QQCCA 

Resistance  per  mile  20°  C 

Cir.  Mils 

Pounds  per  mile  ohm  0°  C 403.5 

Pounds  per  mile  ohm  20°  C 435.6 

Temperature  Coefficient  per  °  C .0039 

Temperature  Coefficient  per  °  F .0022 


[185] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


TABLE  8 
COPPER  CLAD  WIRI 
Physical  constants  of  commercial  wire. 

I 

Average 

values 

30% 

40% 

Percent  Conductivity  (Matthiessen's  Standard  100) 
Specific  Gravity              

29M% 
8.25 

39% 
8.25 

Pounds  in  1  cubic  inch 

.298 

.298 

0.00281 

0.00281 

Ultimate  Strength  =-~      

60,000 

100,000 

19  000  000 

21  000  000 

.000012 

.000012 

.0000067 

.0000067 

Melting  Point  in  °  C.                               

Melting  Point  in  °  F 

Specific  Heat  (watt-seconds  to  heat  1  Ib.  1°  C.)  
Thermal     Conductivity     (watts    through    cu.    in., 
temperature  gradient  1°  C.)  

•• 

Resistance  : 
Microhms  per  centimeter  cube  0°  C  
Microhms  per  inch  cube  0°  C 

•• 

•• 

Ohms  per  mil-foot  20°  C  

35.5 

26.6 

Resistance  per  mile  0°  C  

Resistance  per  mile  20°  C 

187,000 

140,000 

Cir.  Mils 

Cir.  Mils 

Pounds  per  mile  ohm  20°  C  

2,775 

2,075 

Temperature  Coefficient  per  °  C,  from  0°  C  

.0044 

Temperature  Coefficient  per  °  F,  from  32°  F  

.0024 

[  186] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


TABLE  9 

STEEL  WIRE 
Physical  constants  of  commercial  wire.     Average  values 

Siemens's 
Martin 

High 
Strength 

Extra  High 
Strength 

Percent    Conductivity    (Matthiessen's 
Standard  100) 

8.7 
7.85 
.283 
.002671 
38000 
75,000 

29,000,000 
.0000118 
.00000662 
1360 
2480 

18.10 
7.13 
108.8 
119.7 
574,000 

7.85 
.283 

69000 
125,000 
29,000,000 

18.47 
7.27 
llf.3 
122.5 
588,000 

7.85 
.283 

112000 
187,000 
29,000,000 

18.88 
7.43 
113.7 
125.0 
600,000 

Specific  Gravity 

Pounds  in  1  cubic  inch  
Pounds  per  1000  ft.  per  circular  mil  .  .  . 
Elastic  Limit  

Ibs. 

*.   8q'mib.Xin. 

Coefficient  of  Linear  Expansion  per  °  C. 
Coefficient  of  Linear  Expansion  per  °  F. 
Melting  Point  in  °  C. 

Melting  Point  in  °  F  

Specific  Heat  (watt-seconds  to  heat  1 
Ib.  1°  C.)  
Thermal  Conductivity  (watts  through 
cu.  in.,  temperature  gradient  1°  C.)  . 
Resistance  : 
Microhms  per  centimeter  cube  0°  C.  . 
Microhms  per  inch  cube  0°  C. 

Ohms  per  mil-foot  0°  C. 

Ohms  per  mil-foot  20°  C. 

Cir.  Mils 
632,000 

Cir.  Mils 
647,000 

Cir.  Mils 

Pounds  per  mile  ohm  0°  C  

Cir.  Mils 
8090 
8900 
.00501 
.00278 

Cir.  Mils 
8270 
9100 
.00501 
.00278 

Cir.  Mils 
8450 
9300 
.00501 
.00278 

Pounds  per  mile  ohm  20°  C  

Temperature  Coefficient  per  °  C  
Temperature  Coefficient  per  °  F  

[  187  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


TABLE  10 
IRON  WIRE 
Physical  constants  of  commercial  wire. 

Average 

values 

B.  B. 

E.  B.  B. 

Percent  Conductivity  (Matthiessen's  Standard  100) 
Specific  Gravity 

19.99 

7.77 

16.8 
7.77 

Pounds  in  1  cubic  inch 

.282 

.282 

Pounds  per  1000  ft.  per  circular  mil  

.00265 

.002652 

Elastic  Limit    

30,000 

Ibs. 

61  000 

55  000 

so.  in. 
Ib.Xin. 

26  000  000 

Modulus  uf  elasticity  in  x  sq-  in>  

.000012 

.000012 

Coefficient  of  Linear  Expansion  per  °  F  

.0000067 

.00000673 

Melting  Point  in  °  C                                      

1635 

Melting  Point  in  °  F                                             

2975 

Specific  Heat  (watt-seconds  to  heat  1  Ib.  1°  C.)  
Thermal     Conductivity     (watts    through     cu.    in., 

209 
1.39 

Resistance  : 

11.3 

9.5 

4.45 

3.74 

68.0 

57.2 

Ohms  per  mil-foot  20°  C  

74.80 

62.92 

Resistance  per  mile  0°  C 

358,000 

302,000 

Cir.  Mils 
395,000 

Cir.  Mils 
332,000 

Pounds  per  mile  ohm  0°  C.                  

Cir.  Mils 
5,000 

Cir.  Mils 
4,270 

5,500 

4,700 

Temperature  Coefficient  per  °  C                            .... 

.005 

.005 

.00278 

.00278 

[  188  ] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


13.  UNITS  OF  RESISTANCE.  The  unit  of  resistance  now 
universally  used  is  the  International  Ohm. 

The  following  table  gives  the  value  and  relation  of  the  principal 
practical  units  of  resistance  which  existed  prior  to  the  establishment 
of  the  International  Units.  (Table  11.) 


TABLE 

11 

Unit 

Interna- 
tional 
Ohm 

B.  A.  Ohm 

Legal 
Ohm  1884 

Siemens's 
Ohm 

International  Ohm 

1 

1.0136 

1.0028 

1  0630 

B.  A.  Ohm  

0.9866 

1. 

0.9894 

1  0488 

Legal  Ohm           

0.9972 

1.0107 

1. 

1  0600 

0.9407 

0  9535 

0  9434 

1 

To  reduce  British  Association  ohms  to  international  ohms  divide 
by  1.0136,  or  multiply  by  0.9866;  and  to  reduce  legal  ohms  to 
international  ohms,  divide  by  1.0028,  or  multiply  by  0.9972,  etc. 

14.  SPECIFIC  RESISTANCE: 
Let     L  =  length  of  conductor. 

A  =  cross  section  of  the  conductor. 
R  =  resistance  of  the  conductor. 
p  =  specific  resistance  of  the  conductor. 


or 


R 


A 
A 


If  "L"  is  measured  in  centimeters  and  "  A"  in  square  centimeters, 
P  is  the  resistance  of  a  centimeter  cube  of  the  conductor.  If  "L"  is 
measured  in  inches  and  "A"  in  square  inches,  p  is  the  resistance  of 
an  inch  cube  of  the  conductor. 

In  telegraph  and  telephone  practice,  specific  resistance  is  sometimes 
expressed  as  the  "weight  per  mile-ohm,"  which  is  the  weight  in 
pounds  of  a  conductor  one  mile  long  having  a  resistance  of  one 
ohm. 

Another  common  way  of  expressing  specific  resistance  is  in  terms 
of  "ohms  per  mil-foot,"  i.  e.,  the  resistance  of  a  round  wire  one  foot 
long  and  0.001  inch  in  diameter;  L  is  then  measured  in  feet  and  A 
in  circular  mils. 

Microhms  per  inch  cube  =0.3937  X  microhms  per  centimeter  cube. 

Pounds    per    mile-ohm 

times  specific  gravity  =57.07  X  microhms  per  centimeter  cube. 

Ohms  per  mil-foot       "  =6.015  X  microhms  per  centimeter  cube. 

[  189] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


15.  SPECIFIC   CONDUCTIVITY   is   the   reciprocal   of   specific 
resistance.     If  c  =  specific  conductivity 


c  = 


cA 
_L_ 
RA 
1 


16.  By  RELATIVE  OR  PERCENTAGE  CONDUCTIVITY  of  a 

sample  is  meant  100  times  the  ratio  of  the  conductivity  of  the  sample 
at  standard  temperature,  to  the  conductivity  of  a  conductor  of  the 
same  dimensions  made  of  the  standard  material  and  at  standard 
temperature.  If  p0  is  the  specific  resistance  of  the  sample  at  stand- 
ard temperature,  and  pa  is  the  specific  resistance  of  the  standard 
at  standard  temperature,  then 


Percentage  conductivity  =  100 


In  comparing  different  materials,  the  specific  resistance  should 
always  be  determined  at  the  standard  temperature,  which  is  usually 
taken  as  0°  Centigrade.  If  it  is  inconvenient  to  measure  the  resist- 
ance of  the  sample  at  the  standard  temperature,  this  may  be  cal- 
culated provided  the  temperature  coefficient  a  of  the  sample  is 
known,  i.  e. 

pt 

po~l+at 

where  pt  is  the  specific  resistance  at  temperature  t. 

17.  MATTHIESSEN'S  STANDARD  CONDUCTIVITY  is  the 
commercial  standard  of  conductivity  and  is  the  conductivity  of  a 
copper  wire  having  the  following  properties  at  a  temperature  of  0°C: 

Specific  gravity 8.89. 

Length 1  meter. 

Weight 1  gram. 

Resistance 141729  ohms. 

Specific  resistance 1.594  microhms  per  cubic  centimeter. 

Relative  conductivity     100%. 


TABLE  12 

MATTHIESSEN'S  STANDARD 

Equivalent  length  of  a 
square  mm. 
mercury  column. 

B.  A. 

units. 

Legal  ohms. 

Interna- 
tional ohms. 

104.8  cms. 

106.0  cms. 

106.3  cms. 

Resistance   at   0°  C.  of  Mat- 
thiessen's  Standard  — 
Meter-gram  soft  copper  
Meter-millimeter  soft  copper  . 
Cubic  centimeter  soft  copper  . 
Mil-foot  soft  copper  

143  65 
.020  57 
.000  001  616 
9.72 

.142  06 
.020  35 
.000  001  598 
9.612 

.141  73 
.0203 
.000  001  594 
9.59 

[  190  ] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


18.  SPECIFIC  RESISTANCE,  RELATIVE  RESISTANCE,  AND 
RELATIVE  CONDUCTIVITY  OF  CONDUCTORS. 


TABLE  13 

Referred  to  Matthiessen's  Standard 

Metals: 

Resistance  in  Microhms 
atO°C 

Relative 
Resistance 
Percent 

Relative 
Conductivity 
Percent 

Centimeter 
Cube 

Inch 
Cube 

Silver  annealed  
Copper,  annealed  .... 
Copper  (Matthiessen's 
Standard)  . 
Gold  (99.9%  pure)  
Aluminum  (99%  pure) 
Zino  
Platinum,  annealed  .  .  . 
Iron    

1.47 
1.55 
1.594 

2.20 
2.58 
5.75 
8.98 
9.07 
12.3 
13.1 
20.4 
35.2 
94.3 
130. 
2400-42,000 
about  4000 
6  x  IQio 

.579 
.610 
.6276 

.865 
1.01 
2.26 
3.53 
3.57 
4.85 
5.16 
8.04 
13.9 
37.1 
51.2 
950-16,700 
about  1590 
2.38  x  10'° 

92.5 
975 
100 

138 
161 
362 
565 
570 
778 
828 
1280 
2210 
5930 
8220 

108.2 
102.6 
100.0 

12.5 
62.1 
27.6 
17.7 
17.6 
12.9 
12.1 
7.82 
4.53 
1.69 
1.22 

Nickel 

Tin  .  . 

Lead 

Antimony  
Mercury 

Bismuth  
Carbon  (graphite)  .... 
Carbon  (arc  light)  .... 
Selenium  

GENERAL 

Liquids    at  18°  C. 

Ohms  per  Centimeter 
Cube 

Ohms  per  Inch  Cube 

Pure  Water 

2650 
30 
4.86 
1.37 
9.18 
1.29 
21.4 

1050 
11.8 
1.93 
.544 
3.64 
.512 
8.54 

Sea  Water  

Sulphuric  acid,  5%  .  .  . 
Sulphuric  acid,  30%  .  . 
Sulphuric  acid,  80%  .  . 
Nitric  acid,  30% 

Zinc  sulphate,  24%  .  . 

19.  TEMPERATURE  COEFFICIENT.  The  resistance  of  a 
conductor  varies  with  the  temperature  of  the  conductor. 

Let     Ro  =  Resistance  at  0° 
R    =  Resistance  at  t° 
ThenR    =R0(l+at). 

a  is  called  the  temperature  coefficient  of  the  conductor.  100  a 
is  the  percentage  change  in  resistance  per  degree  ^change  in  tem- 
perature. 

The  following  values  of  the  temperature  coefficient  have  been 
found  for  temperatures  measured  in  degrees  Centigrade  and  in 
degrees  Fahrenheit.  The  coefficients  vary  considerably  with  the 
purity  of  the  conductor.  (Table  15.) 

[191] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


TABLE  14 

TEMPERATURE  COEFFICIENTS 

Table  of  temperature  variations  in  the  resistance  of  pure  soft 

copper  according  to  Matthiessen's  standard  and  formulae. 

g.i 

rt 

* 

Matthiessen  meter-gram  standard 

£§ 

o  O 

resistance. 

5° 

ll§ 

a 

2  £  . 

g.sl 

j3 

|61 

111 

*£H 

o3 

B.  A. 

Legal 

Interna- 
tional 

M  VM 

0>T3   6fl 
pH 

fa 

1 

units. 

ohms. 

ohms. 

0 

i. 

0. 

0.143  65 

0.142  06 

0.141  73 

1 

1.003  876 

0.001  680  1 

0.144  21 

0.142  61 

0.142  28 

2 

1.007  764 

0.003  358  8 

0.144  77 

0.143  17 

0.142  83 

3 

1.011  66 

0.005  036  2 

0.145  33 

0.143  72 

0.143  38 

4 

1.015  58 

0.006  712  1 

0.145  89 

0.144  27 

0.143  94 

5 

1.019  5 

0.008  386  4 

0.146  45 

0.144  83 

0.144  49 

6 

1.023  43 

0.010  059  3 

0.147  02 

0.145  39 

0.145  05 

7 

1.027  38 

0.011  730  7 

0.147  59 

0.145  95 

0.145  61 

8 

1.031  34 

0.013  400  3 

0.148  15 

0.146  51 

0.146  17 

9 

1.035  31 

0.015  068  3 

0.148  73 

0.147  08 

0.146  73 

10 

1.039  29 

0.016  734  6 

0.149  3 

0.147  64 

0.147  S 

11 

1.043  28 

0.018  399  3 

0.149  87 

0.148  21 

0.147  86 

12 

1.047  28 

0.020  062  1 

0.150  45 

0.148  78 

0.148  43 

13 

1.051  29 

0.021  723 

0.151  02 

0.149  35 

0.149 

14 

1.055  32 

0.023  382  1 

0.151  6 

0.149  92 

0.149  57 

15 

1.059  35 

0.025  039 

0.152  18 

0.150  49 

0.150  14 

16 

1.063  39 

0.026  694 

0.152  77 

0.151  07 

0.150  71 

17 

1.067  45 

0.028  348 

0.15334 

0.151  64 

0.151  29 

18 

1.071  52 

0.029  999 

0.153  93 

0.152  22 

0.151  86 

19 

1.075  59 

0.031  648 

0.154  51 

0.152  8 

0.152  44 

20 

1.079  68 

0.033  294 

0.155  1 

0.153  38 

0.153  02 

21 

1.083  78 

0.034  939 

0.155  69 

0.153  96 

0.153  6 

22 

1.087  88 

0.036  581 

0.156  28 

0.154  55 

0.154  18 

23 

1.092 

0.038  222 

0.156  87 

0.155  13 

0.154  77 

24 

1.096  12 

0.039  859 

0.157  46 

0.155  72 

0.155  35 

25 

1.100  26 

0.041  494 

0.158  06 

0.15631 

0.155  94 

26 

1.104  4 

0.043  127 

0.158  65 

0.156  89 

0.156  53 

27 

1.108  56 

0.044  758 

0.159  25 

0.157  48 

0.157  11 

28 

1.112  72 

0.046  385 

0.159  85 

0.158  08 

0.157  7 

29 

1.116  89 

0.048  Oil 

0.160  44 

0.158  67 

0.1583 

30 

1.121  07 

0.049  633 

0.161  05 

0.159  26 

0.158  89 

40 

1.163  32 

0.065  699 

0.167  11 

0.165  26 

0.164  88 

50 

1.206  25 

0.081  436 

0.173  28 

0.171  36 

0.17095 

60 

1.249  65 

0.096  787 

0.179  52 

0.177  53 

0.177  11 

70 

1.293  27 

0.111  687 

0.185  78 

0.183  72 

0.183  29 

80 

1.336  81 

0.126  069 

0.192  04 

0.189  91 

0.189  46 

90 

1.379  95 

0.139  863 

0.198  23 

0.196  04 

0.195  58 

100 

1.422  31 

0.152  995 

0.204  32 

0.202  06 

0.201  58 

[  192] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


TABLE  15 
TEMPERATURE  COEFFICIENTS 

Pure  Metals 

Centigrade 
a 

Fahrenheit 

a 

Silver,  annealed  

0.00400 
0.00428 
0.00377 
0.00423 
0.00406 
0.00247 
0.00625 
0.0062 
0.00440 
0.00411 
0.00389 
0.00072 
0.00354 

0.00222 
0.00242 
0.00210 
0.00235 
0.00226 
0.00137 
0.00347 
0.00345 
0.00245 
0.00228 
0.00216 
0.00044 
0.00197 

Copper,  annealed  
Gold  (99  9%) 

Aluminum  (99%)  
Zinc  

Platinum,  annealed  

Nickel 

Tin.  . 

Lead                                         

Antimony  

Mercury                               

Matthiessen's  formula  for  soft  copper  wire 

R  =  Ro  (1 + .003871 + .00000597t2) . 

The  wire  used  by  Matthiessen  was  as  pure  as  could  be  obtained 
at  the  time  (1860),  but  in  reality  contained  considerable  impurities; 
the  above  formula,  therefore,  is  not  generally  applicable.  Later 
experiments  have  shown  that  for  all  practical  work  the  above 
equation  for  copper  wire  may  be  written 

R  =R0  (1  +  .0042t)  for  t  in  °C. 

TEMPERATURE  COEFFICIENT  OF  COPPER 
A.  I.  E.  E. 

The  fundamental  relation  between  the  rise  of  temperature  and  the 
increase  of  resistance  of  copper  may  be  expressed  thus: 

Rt  =  Rt1(l+atl[t-t1]) 

where  Rt  is  the  resistance  at  any  temperature  t  deg.  Cent. ;  R^  is  the 
resistance  at  any  " initial  temperature"  (or  " temperature  of  ref- 
erence") ti  deg.  cent.;  and  atx  is  the  temperature  coefficient  from 
and  at  the  initial  temperature  ti  deg.  cent.  Obviously  the  tem- 
perature coefficient  is  different  for  different  initial  temperatures,  and 
this  variation  is  shown  in  the  horizontal  rows  of  Table  16.  ^  Further- 
more, it  has  been  shown  that  the  temperature  coefficient  is  different 
for  different  conductivities,  and  that  the  temperature  coefficient  is 
substantially  proportional  to  the  conductivity.  The  results  of  this 
simple  law  are  shown  by  the  vertical  columns  of  Table  16. 
7  [  193  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


TABLE  16 

TEMPERATURE  COEFFICIENTS  OF  COPPER  FOR 
DIFFERENT  INITIAL  TEMPERATURES  AND 
DIFFERENT  CONDUCTIVITIES 

Ohms  per 
meter- 
gram 
at  20 
deg.  Cent. 

Per 
cent 
con- 
duc- 
tivity 

ao 

ais 

0,20 

0-25 

aso 

0.50 

-T 
"Inferred 
absolute 
zero" 

0.16108 
0.15940 
0.15776 
0.15727 
0  15614 
0.15557 
0.153022 

95 
96 
97 
97.3 
98 
99 
100 

101 

0.00405 
0.00409 
0.00414 
0.00415 
0.00418 
0.00423 
0.00428 

0.00432 

0.00381 
0.00386 
0.00390 
0.00391 
0.00394 
0.00398 
0.00402 

0.00406 

0.00374 
0.00378 
0.00382 
0.00383 
0.00386 
0.00390 
0.00394 

0.00367 
0.00371 
0.00375 
0.00376 
0.00379 
0.00383 
0.00386 

0.00390 

0.00361 
0.00364 
0  00368 
0.00369 
0.00372 
0.00375 
0.00379 

0.00383 

0.00336 
0.00340 
0.00343 
0.00344 
0.00346 
0.00349 
0.00352 

0.00355 

-247.2 
-244.4 
-241.7 
-240.9 
-239.0 
-236.4 
-233.8 

-231.3 

0.15151 

0.00398 

The  quantity  ( — T)  given  in  the  last  column  of  Table  16  is  the 
calculated  temperature  on  the  Centigrade  scale  at  which  copper  of 
the  particular  conductivity  concerned  would  have  zero  electrical  re- 
sistance provided  the  temperature  coefficient  between  0 deg.  Cent,  and 
100  deg.  Cent,  applied  continuously  down  to  the  absolute  zero.  The 
usefulness  of  this  "inferred  absolute  zero  temperature  of  resistance" 
in  calculating  temperature  rise  is  evident  from  the  following  formula: 

Rt~Rti  rr-i-t  ^ 
t— ti  =  — — (l-t-ti; 

Ivtj 

The  presentation  of  the  above  table  is  intended  to  emphasize  the 
desirability  of  determining  the  temperature  coefficient  rather  than 
assuming  it.  Actual  experimental  determination  is  facilitated  by 
the  proportional  relation  between  the  temperature  coefficient  and 
the  conductivity;  a  measurement  of  either  quantity  gives  both. 
However,  if  a  temperature  coefficient  must  be  assumed,  the  best 
value  to  take  for  average  commercial  annealed  copper  wire  is  that 
given  in  Table  16  for  100  percent  conductivity,  viz., 

a0=  0.00428,  020  =0.00394,  a25=  0.00386 

This  is  the  value  recommended  for  wire  wound  on  instruments  and 
machines,  since  they  are  generally  wound  with  annealed  wire,  and 
experiments  have  shown  that  the  distortions  due  to  the  winding  of 
the  wire  do  not  appreciably  affect  the  temperature  coefficient. 

If  a  value  must  be  assumed  for  hard-drawn  copper  wire,  the  value 
recommended  is  that  given  in  Table  16  for  97.3  percent  conductivity 
viz., 

a0  =0.00415,  a20  =0.00383,  o25  =0.00376 

The  temperature  coefficients  in  Fahrenheit  degrees  are  given  by 
dividing  any  a  above  by  1.8.  Thus,  the  20  deg.  Cent,  or  68  deg.  Fahr. 
temperature  coefficient  for  copper  of  100  percent  conductivity  is 
0.00394  per  deg.  Cent.,  or  0.00219  per  deg.  Fahr. 

[  194] 


CONDUCTORS  AND  WIRE  TABLES 
WIRE  GAUGES 


Sec.  3 


20.  AMERICAN  STEEL  AND  WIRE  GAUGE  is  generally  used 
in  America  for  iron  and  steel  wire. 

21.  BROWN  AND  SHARPE  GAUGE  is  the  standard  gauge  used 
for  wires  for  electrical  purposes,  (iron  and  steel  wire  excepted). 

22.  BIRMINGHAM  GAUGE  is  used  largely  in  England  and  also 
in  this  country  for  wires  (excepting  iron  wire)  other  than  those  made 
especially  for  electrical  purposes. 

23.  COMPARISON  OF  WIRE  GAUGES.     The  sizes  of  wires  are 
ordinarily  expressed  by  an  arbitrary  series  of  numbers.     Unfortu- 
nately there  are  several  independent  numbering  methods,  so  that  it 
is  alwa}rs  necessary  to  specify  the  method  or  wire  gauge  used. 
Table   17  gives  the  numbers  and  diameters  in  decimal  parts  of 
an  inch  for  the  various  wire  gauges  used  in  this  country  and  Eng- 
land. 


TABLE  17 

COMPARATIVE  SIZES  WIRE  GAUGE  IN  DECIMALS 

OF  AN  INCH 

No.  of 
Wire 

American 
Steel  & 

American 
Standard 

Birming- 
ham or 

British 
Imperial 

Old  English 
or 

French. 

Gauge. 

Wire 

(B.  &  S.) 

Stubs'. 

Standard. 

London. 

0000000 

.4900 

.500 

000000 

.4615 

.58000 

.464 

00000 

.4305 

.51650 

.500 

.432 

0000 

.3938 

.46000 

.454 

.400 

.4540 

000 

.3625 

.40964 

.425 

.372 

.4250 

00 

.3310 

.36480 

.380 

.348 

.3800 

0 

.3065 

.32486 

.340 

.324 

.3400 

1 

.2830 

.28930 

.300 

.300 

.3000 

.0325 

2 

.2625 

.25763 

.284 

.276 

.2840 

.040 

3 

.2437 

.22942 

.259 

.252 

.2590 

.050 

4 

.2253 

.20431 

.238 

.232 

.2380 

.0625 

5 

.2070 

.18194 

.220 

.212 

.2200 

.068 

6 

.1920 

.16202 

.203 

.192 

.2030 

.083 

7 

.1770 

.14428 

.180 

.176 

.1800 

.097 

8 

.1620 

.12849 

.165 

.160 

.1650 

.110 

9 

.1483 

.11443 

.148 

.144 

.1480 

.120 

10 

.1350 

.10189 

.134 

.128 

.1340 

.135 

11 

.1205 

.09074 

.120 

.116 

.1200 

.149 

12 

.1055 

.08081 

.109 

.104 

.1090 

.162 

13 

.0915 

.07196 

.095 

.092 

.0950 

.172 

14 

.0800 

.06408 

.083 

.080 

.0830 

.185 

15 

.0720 

.05706 

.072 

.072 

.0720 

.197 

16 

.0625 

.05082 

.065 

.064 

.0650 

.212 

17 

.0540 

.04525 

.058 

.056 

.0580 

.225 

18 

0475 

.04030 

.049 

.048 

.0490 

.238 

19 

.0410 

.03589 

.042 

.040 

.0400 

.250 

20 

.0348 

.03196 

.035 

.036 

.0350 

.263 

[  195] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


24.     LAW  OF  THE  BROWN  AND   SHARPE   GAUGE.     The 

diameters  of  wires  of  the  B.  and  S.  gauge  are  obtained  from  the 
geometric  series  in  which  No.  0000=0.4600  inch  and  No.  36  =  .005 


TABLE  18 

DIAMETER  AND  CROSS-SECTION  AREA 

SOLID  WIRE 

Brown  & 
Sharpe  Gauge 

Diameter  of  Wire 

Cross-sectional  Area 

In  Inches 

In 
Millimeters 

Circular  Mils 
(d2) 
d=.  001  Inch 

Square  Inch 
(d»  x  .7854) 

Square 
Millimeter 

0000 
000 
00 
0 

.4600 
.4096 
.3648 
.3250 

11.683 
10.404 
9.266 
8.255 

211600. 
167772. 
133079. 
105625. 

.166190 
.131770 
.104520 
.082958 

107.219 
85.011 
67.432 
53.521 

1 

2 
3 

4 

.2893 
.2576 
.2294 
.2043 

7.348 
6.543 
5.827 
5.189 

83694. 
66358. 
52624. 
41738. 

.065733 
.052117 
.041331 
.032781 

42.408 
33.624 
26.665 

2*.  149 

5 
6 

7 
8 

.1819 
.1620 
.1443 
.1285 

4.620 
4.115 
3.665 
3.264 

33088. 

26244. 
20822. 
16512. 

.025987 
.020612 
.016354 
.912969 

16.766 
13.298 
10.550 
8.3666 

9 
10 
11 
12 

.1144 
.1019 
.0907 
.0808 

2.906 
2.588 
2.304 
2.052 

13087. 
10384. 
8226.5 
6528.6 

.010279 
.0081553 
.0064611 
.0051276 

6.6313 
5.2614 
4.1684 
3.3081 

13 
14 
15 
16 

.0720 
.0641 
.0571 
.0508 

1.829 
1.628 
1.450 
1.290 

5184.0 
4108.8 
3260.4 
2580.6 

.0040715 
.0032271 
.0025607 
.0020268 

2.6267 
2.0819 
1.6520 
1.307€x 

17 
18 
19 
20 

.0453 
.0403 
0359 
.0320 

1.151 
1.024 
.9119 
.8128 

2052.1 
1624.1 
1288.8 
1024.0 

.0016117 
.0012756 
.0010122 
.00080425 

1.0398 
.82294 
.65304 
.51887 

inch,  the  nearest  fourth  significant  figure  being  retained  in  the  areas 
and  diameters  so  deduced.     Brown  and  Sharpe  tables  are  derived 
from  the  following  formulae: 
Let 

n=gauge  number  (0000=  -3;000=  -2;00=  -1). 
d  =  diameter  of  wire  in  inches. 
Cir.  mils  =  area  in  circular  mils. 

r  =  resistance  in  ohms  per  1000  ft.  at  20°  C. 
w  =  weight  in  pounds  per  1000  ft. 
[  196] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 

Then 

0.3249 
~1.123n 

105,500 


r  =  0.09811  Xl.261n 
319.5 


A  useful  approximate  formula  for  resistance  per  1000  feet  at  about 
20°  C.  is  as  follows; 

r  =  0.!X(2)|  ((2)*  =  1.26;  (2)*  =  1.59.) 

From  this  it  is  seen  that  an  increase  of  3  in  the  wire  number 
corresponds  to  doubling  the  resistance  and  halving  the  cross  section 
and  weight.  Also,  that  an  increase  of  10  in  the  wire  number  in- 
creases the  resistance  10  times  and  diminishes  the  cross  section  and 
weight  to  Yio  their  original  value. 

25.  WIRE  STRANDS.  Wires  larger  than  No.  0000  B.  and  S.  are 
seldom  made  solid,  but  are  built  up  of  a  number  of  small  wires  into  a 
strand.  The  group  of  wires  is  called  a  "strand";  the  term  "wire" 
being  reserved  for  the  individual  wires  of  the  strand.  Strands  are 
usually  built  up  of  wires  of  such  a  size  that  the  cross  section  of  the 
metal  in  the  strand  is  the  same  as  the  cross  section  of  a  solid  wire 
having  the  same  gauge  number. 

If  n=  number  of  concentric  layers  around  one  central  strand, 

Al       3  (n2-f-n)-f-l  metal  area 

then  —  7^~-r~^r~  =  ratio  of  -  rp-  r-j  — 

available  area 


The  number  of  wires  that  will  strand  will  be3n  (n+1)  +1. 


TABLE  19 

WIRE  STRANDS 

Number  of  Strands 

Metal  area 

available  area 

1 
7 
19 
37 
61 
91 

1.000 
.778 
.760 
.755    ..,..: 
.753             ' 
.752 

[  197  ] 


Sec.  3  CONDUCTORS  AND  WIRE  TABLES 

26.  ILLUSTRATIONS  OF  BARE  WIRE,  STRAND  AND  CABLE 


BARE  WIRE 


STRAND 


Full  Sizes  of  Wire 


B.  AS. 
Gauge 


Concentric 

Strand, 

37  Wires 


10 
11 
12 
13 
14 
15 
16 

[198] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


TABLE  20 

CURRENTS 

FUSING  EFFECTS  OF  CURRENTS 

Table  giving  the  diameters  of  wires  of  various  materials  which 

will  be  fused  by  a  current  of  given  strength 

Current  in  amperes 

Diameters  in  inches. 

1 

0 

O 

Aluminum 

Platinum 

German 
Silver 

Platinoid 

1 

a 

£ 

jb 

I1 

3 

1 
2 
3 
4 
5 

0.002  1 
0.003  4 
0.004  4 
0.005  3 
0.006  2 

0.002  6 
0.004  1 
0.005  4 
0.006  5 
0.007  6 

0.003  3 
0.005  3 
0.007 
0.008  4 
0.009  8 

0.003  3 
0.005  3 
0.006  9 
0.008  4 
0.009  7 

0.003  5 
0.005  6 
0.007  4 
0.008  9 
0.010  4 

0.004  7 
0.007  4 
0.009  7 
0.011  7 
0.013  6 

0.007  2 
0.011  3 
0.014  9 
0.018  1 
0.021 

0.008  3 
0.013  2 
0.017  3 
0.021 
0.024  3 

0.008  1 
0.012  8 
0.016  8 
0.020  3 
0.0236 

10 
15 
20 
25 
30 

0.009  8 
0.012  9 
0.015  6 
0.018  1 
0.020  5 

0.012 
0.015  8 
0.019  1 
0.022  2 
0.025 

0.015  5 
0.020  3 
0.024  6 
0.028  6 
0.032  3 

0.015  4 
0.020  2 
0.024  5 
0.028  4 
0.032 

0.016  4 
0.021  5 
0.026  1 
0.030  3 
0.034  2 

0.021  6 
0.028  3 
0.034  3 
0.039  8 
0.045 

0.033  4 
0.043  7 
0.052  9 
0.061  4 
0.069  4 

0.038  6 
0.050  6 
0.061  3 
0.071  1 
0.080  3 

0.037  5 
0.049  1 
0.059  5 
0.069 
0.077  9 

35 
40 
45 
50 
60 

0.022  7 
0.024  8 
0.026  8 
0.028  8 
0.032  5 

0.027  7 
0.030  3 
0.032  8 
0.035  2 
0.039  7 

0.035  8 
0.039  1 
0.0423 
0.045  4 
0.051  3 

0.035  6 
0.038  8 
0.042 
0.045 
0.050  9 

0.037  9 
0.0414 
0.044  8 
0.048 
0.054  2 

0.0498 
0.0545 
0.058  9 
0.063  2 
0.071  4 

0.076  9 
0.084 
0.090  9 
0.097  5 
0.110  1 

0.089 
0.0973 
0.105  2 
0.112  9 
0.127  5 

0.086  4 
0.0944 
0.102  1 
0.109  5 
0.123  7 

70 
80 
90 
100 
120 

0.036 
0.039  4 
0.042  6 
0.045  7 
0.051  6 

0.044 
0.048  1 
0.052 
0.055  8 
0.063 

0.056  8 
0.062  1 
0.067  2 
0.072 
0.081  4 

0.056  4 
0.061  6 
0.066  7 
0.071  5 
0.080  8 

0.0601 
0.065  7 
0.071  1 
0.076  2 
0.086  1 

0.079  1 
0.086  4 
0.093  5 
0.100  3 
0.113  3 

0.122 
0.133  4 
0.144  3 
0.154  8 
0.174  8 

0.141  3 
0.154  4 
0.167  1 
0.179  2 
0.202  4 

0.137  1 
0.149  9 
0.162  1 
0.173  9 
0.196  4 

140 
160 
180 
200 
225 

0.057  2 
0.062  5 
0.067  6 
0.072  5 
0.078  4 

0.0698 
0.076  3 
0.082  6 
0.088  6 
0.095  8 

0.090  2 
0.098  6 
0.1066 
0.114  4 
0.123  7 

0.089  5 
0.097  8 
0.105  8 
0.113  5 
0.122  8 

0.095  4 
0.104  3 
0.112  8 
0.121 
0.130  9 

0.125  5 
0.137  2 
0.148  4 
0.159  2 
0.172  2 

0.193  7 
0.211  8 
0.229  1 
0.245  7 
0.265  8 

0.224  3 
0.245  2 
0.265  2 
0.284  5 
0.307  7 

0.217  6 
0.237  9 
0.257  3 
0.276 
0.298  6 

250 
275 
300 

0.084  1 
0.089  7 
0.095 

0.102  8 
0.109  5 
0.116  1 

0.132  7 
0.141  4 
0.149  8 

0.131  7 
0.140  4 
0.148  7 

0.140  4 
0.149  7 
0.158  6 

0.184  8 
0.196  9 
0.208  6 

0.285  1 
0.303  8 
0.322 

0.330  1 
0.351  8 
0.372  8 

0.320  3 
0.341  7 
0.361  7 

[  199  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


27.  HEATING  EFFECTS  OF  CURRENT. 

If  a  continuous  current  of  electricity  flows  through  any  conductor, 
a  certain  definite  portion  of  the  electrical  energy  supplied  to  the 
conductor  will  be  required  to  overcome  its  resistance  and  transmit 
the  current  between  any  two  points  in  the  conductor.  This  energy 
of  transmission,  as  it  is  called,  is  never  lost,  but  is  transformed  into 
heat  energy.  Heat  will  be  developed  whenever  any  electric  current 
flows  through  any  conductor,  or  part  of  conductor,  the  amount  of 
heat  being  directly  proportional  to  the  resistance  of  the  conductor 
and  to  the  square  of  the  current  flowing.  The  amount  of  heat 
measured  in  calories  will  equal 

II  =  0.24  PR  t 

Where  H  represents  calories  of  heat  produced 
I  current  in  amperes 

R  resistance  of  conductor  in  ohms, 

t  "          time  in  seconds  that  the  current  flows. 

If  heat  be  developed  in  the  conductor  faster  than  it  can  be  dissi- 
pated from  the  surface  by  radiation  and  convection  the  temperature 
will  rise.  The  allowable  safe  temperature  rise  is  one  of  the  limiting 
features  of  the  current  carrying  capacity  of  any  conductor.  Since 
the  rate  at  which  heat  will  be  dissipated  from  any  conductor  will 
depend  upon  many  conditions,  such  as  its  size  and  structure,  the 
kind  and  amount  of  insulation,  if  any,  and  its  location  with  respect 
to  other  bodies,  it  is  not  possible  to  give  any  general  definite  rule 
for  carrying  capacity  that  will  be  true  for  all  conditions.  The  fol- 
lowing empirical  formula  will  give  approximate  values  for  the  cur- 
rent I  flowing  through  a  solid  conductor,  or  through  each  conductor 
of  a  multiple  conductor  cable  which  will  cause  a  rise  in  temperature 
of  t  degrees  C. 

I  =  C 

In  this,  d  represents  the  diameter  of  the  bare  wire  or  strand  in 
inches,  K  is  the  resistance  per  mil-foot  of  the  wire  at  allowable 
elevated  temperature  t  taken  from  the  curves  given  in  Fig.  77 
and  C  is  a  constant  having  the  following  values  for  different  con- 
ditions. 


TABLE  21 

Location  and  Kind  of  Conductor 

Values  of  Con-                 /    d8 
stant  C  in  Expression  of  CA/  *j£ 

Solid  Conductor 

Stranded  Conductor 

Bare  overhead  wires  out  of  doors  ..... 

1250 
660 

530 

1100 
610 

490 

Single  conductor  rubber  covered  cable  in 
still  air  

[  200  ] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


The  heat  radiating  surface  of  any  conductor  varies  as  the  diameter 
of  the  conductor, Awhile  the  current  carrying  capacity,  depending 
on  the  number  of  circular  mils,  will  vary  as  the  square  of  the  diameter. 
In  consequence,  the  current  density  in  large  conductors  will  be  less 


FIG.  77. — Resistance  per  Mil-Foot  of  Pure  Copper  at  Various  Temperatures  and 

I    d» 
Conductivities.     Values  of  K  in  expression  y*  A/*  "K 

than  in  small  conductors  for  an  equal  temperature  rise.  It  has  been 
found  impracticable  on  this  account  to  use  insulated  conductors 
larger  than  2,000,000  c.  m.,  except  in  special  cases. 


[201] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


TABLE  22 

HEATING  EFFECTS  OF  CURRENTS 

Bare  copper  in  still  air 

Rise  in  temperature,  degrees  Centigrade. 

10° 

20° 

40° 

80° 

I 

4! 

i 

4J 

V 

c3 

j£ 
I 

4 

• 

1 

,M 

J 

i 

M 

a 

<j 

« 

m 

m 

5 

PQ 

3 

(XJ 

2 

Diameters    of    wires   in    mils. 

1  000 

968 

911 

750 

950 

930 

878 

723 

900 

]  ] 

893 

844 

695 

850 

858 

809 

666 

800 

.. 

i  boo 

823 

771 

638 

750 

950 

785 

734 

610 

700 

960 

900 

748 

696 

580 

650 

910 

850 

708 

660 

550 

600 

858 

800 

668 

621 

518 

575 

833 

775 

648 

603 

503 

550 

995 

980 

808 

750 

628 

583 

488 

525 

978 

948 

780 

725 

607 

563 

461 

500 

960 

913 

751 

700 

584 

543 

455 

475 

925 

880 

723 

675 

563 

523 

439 

450 

895 

843 

696 

648 

541 

501 

421 

425 

860 

808 

669 

620 

520 

479 

406 

400 

i  boo 

820 

770 

641 

592 

498 

457 

387 

375 

950 

783 

731 

612 

564 

475 

435 

369 

350 

900 

745 

690 

581 

536 

452 

413 

350 

325 

850 

708 

654 

550 

506 

428 

390 

331 

300 

800 

668 

615 

519 

475 

403 

366 

312 

275 

750 

628 

575 

487 

444 

377 

341 

292 

250 

696 

586 

534 

453 

412 

351 

317 

272 

225 

642 

545 

494 

419 

379 

323 

291 

252 

200 

586 

500 

453 

384 

345 

296 

265 

229 

175 

530 

454 

406 

349 

310 

266 

239 

208 

150 

470 

404 

360 

311 

274 

226 

210 

194 

125 

408 

352 

308 

270 

235 

206 

182 

161 

100 

343 

300 

258 

226 

195 

170 

150 

135 

90 

315 

272 

237 

208 

178 

158 

137 

123 

80 

286 

246 

214 

196 

161 

143 

124 

112 

70 

259 

220 

190 

170 

143 

127 

110 

100 

60 

226 

194 

167 

150 

125 

112 

97 

87 

50 

191 

167 

142 

130 

106 

95 

82 

74 

40 

156 

140 

117 

108 

86 

78 

68 

61 

30 

120 

111 

90 

85 

66 

60 

54 

48 

20 

82 

76 

63 

60 

45 

44 

40 

36 

10 

40 

38 

37 

35 

30 

28 

26 

24 

[202  ] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


TABLE  23 

HEATING  EFFECTS  OF  CURRENTS 

Bare  copper  suspended  outdoors 

Rise  in  temperature,  degrees  Centigrade. 

5° 

10° 

20° 

40° 

I 

1 

1 

1 

1 

1 

1 

f 

1 

'* 

« 

« 

n 

A 

« 

m 

3 

Diameters  of  wires  in  mils. 

1  000 

962 

932 

771 

745 

620 

594 

950 

928 

897 

744 

720 

595 

572 

900 

894 

865 

715 

692 

574 

552 

850 

868 

843 

689 

665 

550 

530 

800 

839 

810 

672 

649 

537 

512 

750 

975 

804 

775 

643 

620 

515 

495 

700 

963 

933 

767 

739 

613 

591 

491 

472 

650 

916 

889 

729 

703 

582 

561 

467 

449 

600 

869 

837 

690 

665 

554 

532 

442 

426 

575 

845 

813 

671 

647 

538 

517 

429 

414 

550 

820 

789 

650 

627 

522 

501 

417 

402 

525 

795 

764 

630 

609 

506 

487 

404 

389 

500 

770 

740 

610 

589 

489 

470 

390 

376 

475 

745 

719 

589 

569 

473 

455 

377 

363 

450 

719 

693 

568 

548 

453 

438 

363 

350 

425 

690 

667 

546 

526 

436 

422 

349 

336 

400 

661 

638 

524 

504 

418 

406 

334 

322 

375 

632 

610 

502 

484 

399 

377 

319 

309 

350 

601 

581 

478 

462 

380 

360 

304 

295 

325 

571 

552 

453 

439 

362 

342 

289 

279 

300 

540 

522 

428 

415 

342 

326 

273 

264 

275 

509 

492 

404 

392 

321 

309 

257 

249 

250 

477 

460 

378 

367 

300 

290 

240 

222 

225 

445 

430 

351 

343 

280 

270 

223 

215 

200 

410 

399 

324 

316 

259 

250 

205 

198 

175 

373 

365 

296 

289 

235 

227 

186 

180 

150 

334 

329 

267 

258 

211 

202 

166 

161 

125 

295 

290 

235 

226 

185 

177 

145 

144 

100 

254 

248 

202 

193 

157 

152 

123 

120 

90 

236 

230 

186 

178 

145 

140 

114 

111 

80 

216 

212 

171 

164 

132 

128 

104 

102 

70 

198 

192 

155 

150 

120 

116 

94 

91 

60 

177 

170 

137 

132 

107 

104 

83 

80 

50 

155 

147 

119 

115 

92 

87 

72 

70 

40 

130 

124 

100 

96 

77 

73 

62 

59 

30 

104 

100 

78 

75 

61 

58 

50 

45 

20 

73 

70 

54 

63 

43 

40 

34 

30 

10 

40 

38 

27 

26 

20 

18 

16 

14 

[  203  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


TABLE  24 

CURRENT  CARRYING  CAPACITY  OF  COPPER  WIRE 

1913  National  Electrical  Code 

B.  &  S.  Gauge 

Amperes 

Circular  Mils. 

Table  A 
Rubber  Insulation 

Table  B 
Other  Insulations 

18 
16 
14 
12 

3 
6 
15 
20 

5 
10 
20 
25 

1,624 
2,583 
4,107 
6,530 

10 
8 
6 
5 

25 
35 
50 
55 

30 
50 
70 
80 

10,380 
16,510 
26,250 
33,100 

4 
3 
2 
1 

70 
80 
90 
100 

90 
100 
125 
150 

41,740 
52,630 
66,370 
83,690 

0 
00 
000 
0000 

125 
150 
175 
225 

200 
225 
275 
325 

105,500 
133,100 
167,800 
211,600 

* 

200 
275 
325 
400 

300 
400 
500 
600 

200,000 
300,000 
400,000 
500,000 

.. 

450 
500 
550 
600 

680 
760 
840 
920 

600,000 
700,000 
800,000 
900,000 

•• 

650 
690 
730 
770 

1000 
1080 
1150 
1220 

1,000,000 
1,100,000 
1,200,000 
1,300,000 

'• 

810 
850 
890 
930 

1290 
1360 
1430 
1490 

1,400,000 
1,500,000 
1,600,000 
1,700,000 

••• 

970 
1010 
1050 

1550 
1610 
1670 

1,800,000 
1,900,000 
2,000,000 

[  204  ] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 

The  current  carrying  capacity  for  other  materials  may  be  found 
by  multiplying  the  current  for  the  same  gauge  or  circular  mil  size 
copper  by  the  square  root  of  the  ratio  of  the  conductivity  of  the 
material  to  the  conductivity  of  copper  or  by  the  square  root  of  the 
ratio  of  the  specific  resistance  of  copper  to  the  specific  resistance  of 
the  material: 

Symbols: 

C  =  Conductivity  of  copper 

C'  =  Conductivity  of  material,  the  current  carrying  capacity  of 
which  is  desired 

p   =  Specific  resistance  of  copper 

P    =  Specific  resistance  of  other  material 

I    =  Cur  rent  carrying  capacity  of  copper 

I'  =  Current  carrying  capacity  of  other  material. 
Then 


Problem  : 

Find  the  current  carrying  capacity  of  a  No.  0,  40%  copper  clad 
solid  wire  and  that  of  a  No.  0,  61%  aluminum  solid  wire,  assuming 
the  current  carrying  capacity  of  No.  0  copper  to  be  200  amperes. 
Copper  Clad. 
C  =1.00 
C'  =  0.4 

Then  I'=20oV)^  =  200X0.632  =  126.4  amperes. 

For  aluminum: 

Resistance  of  copper  from  Table  35  =  0.09811 

Resistance  of  aluminum  from  Table  35=0.1608 


I'  =  200  =  200X0.78  =  156  amperes. 


Note:  The  above  formulae  apply  to  direct  current  problems. 
When  alternating  current  is  used,  it  is  necessary  to  correct  the  re- 
sistances of  all  cables  for  skin  effect. 

28.  EFFECTIVE  RESISTANCE—  SKIN  EFFECT.  The  effective 
resistance  of  a  circuit  to  an  alternating  current  depends  on  the  shape 
of  the  circuit;  the  specific  resistance,  permeability,  cross  section 
and  shape  of  the  conductor,  and  the  frequency  of  the  current.  The 
current  density  over  the  cross  section  of  the  conductor  is  a  minimum 
at  the  center,  increasing  to  a  maximum  at  the  periphery;  in  a  solid 
conductor  of  large  cross  section  the  current  is  confined  almost 
entirely  to  an  outer  shell  or  "skin."  "The  Skin  Effect  Factor"  is 
the  number  by  which  the  resistance  of  the  circuit  to  a  continuous 
current  must  be  multiplied  to  give  the  effective  resistance  to  an  alter- 

[  205  ] 


Sec.  3  CONDUCTORS  AND  WIRE  TABLES 

nating  current.  The  following  formulae  and  table  give  the  "Skin 
Effect  Factor"  for  a  straight  wire  of  circular  cross  section,  the  re- 
turn wire  of  the  circuit  being  assumed  sufficiently  remote  to  be 
without  effect,  which  is  practically  the  case  in  an  aerial  transmission 
line. 

Let 

R  =  resistance  of  wire  in  ohms  to  a  continuous  current 

R'  =  effective  resistance  of  wire  in  ohms  to  an  alternating  current 

f    =  cycles  per  second 

A  =  cross  section  of  wire  in  circular  mils 

M   =  permeability  of  wire  in  C.  G.  S.  units 

t    =  temperature  in  °  C. 

a  =  temperature  coefficient  per  °  C. 

C  =  percentage  conductivity  of  wire  referred  to  Matthiessen's 

copper  standard  at  0°  C. 
Then 

R'     f      A.        f(fMCA) 

!T=functlonof(TW 

This  function  is  a  complex  one;  however,  for 


the  approximate  formula-^-  v  i  j_   +  +0.28 

Jtv  *     JL  ~\     &ti 

is  sufficiently  accurate  for  all  practicable  purposes. 

Problem: 

Find  the  approximate  resistance  of  500,000  cir.  mils  stranded 
copper  cable  carrying  a  60  cycle  current. 

f  A  =  500,000  X  60  =  30,000,000 
Factor  from  Table  25  =  1.025 
Resistance  from  Table  36  =  0.02116 
Effective  resistance  =0.02116X1.025  =  0.02169 

Problem: 

Find  the  approximate  effective  resistance  of   No.  0000  B.  &  S. 
40%  copper  clad  solid  wire  carrying  a  60  cycle  current  of  80  amperes. 
Find  the  percent  increase  in  resistance  from  Fig.  79  =  22.8% 
Find  the  resistance  of  No.  0000  copper  clad  from  Table  35  =  0.125 
Effective  resistance  =  0. 125  X  1.228 = 0. 1535 


[206] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


TABLE  25 

SKIN  EFFECT  FACTORS  AT  20°  C.  FOR   STRAIGHT 

WIRES  HAVING  CIRCULAR  CROSS 

SECTION 

Product  of 
Circular  Mils 
by  Cycles  per 
Second. 
fXA 

Factor*  for 
Iron  Wire. 
C=17 
M=150 

Product  of  Circu- 
lar Mils  by  Cycles 
per  Second. 
fXA 

Factor  for 

Copper  Wire. 
C=100 
M=l 

Aluminum 
Wire. 
C=62 
M=l 

500,000 
1,000,000 
2,000,000 
3,000,000 

1.000 
1.015 
1.068 
1.144 

5,000,000 
10,000,000 
20,000,000 
30,000,000 

1.000 
1.000 
1.008 
1.025 

1.000 
1.000 
1.000 
1.006 

4,000,000 
5,000,000 
6,000,000 
7,000,000 

1.234 
1.332 
1.435 
1.535 

40,000,000 
50,000,000 
60,000,000 
70,000,000 

1.045 
1.070 
1.096 
1.126 

1.015 
1.026 
1.040 
1.053 

8,000,000 
9,000,000 
10,000,000 
12,500,000 

1.628 
1.714 
1.795 
1.974 

80,000,000 
90,000,000 
100,000,000 
125,000,000  . 

1.158 
1.195 
1.230 
1.332 

1.069 
1.085 
1.104 
1.151 

15,000,000 
17,500,000 
20,000,000 
25,000,000 

2.14 
2.29 
2.42 
2.68 

150,000,000 
175,000,000 
200,000,000 
250,000,000 

1.433 
1.530 
1.622 
1.790 

1.206 
1.266 
1.330 

1.455 

30,000,000 
35,000,000 
40,000,000 
45,000,000 

2.90 
3.11 
3.31 
3.49 

300,000,000 
350,000,000 
400,000,000 
450,000,000 

1.937 
2.07 
2.20 
2.31 

1.575 
1.686 
1.787 
1.879 

50,000,000 
55,000,000 
60,000,000 

3.67 
3.83 
3.99 

500,000,000 
550,000,000 
600,000,000 

2.42 
2.53 
2.63 

1.965 
2.05 
2.13 

*  This  corresponds  to  E.  B.  B.  telegraph  wire  for  telephone  currents.  The 
permeability  n  is  not  constant,  but  varies  with  the  current  density,  therefore  the 
table  for  iron  wire  should  be  used  with  very  great  care  and  only  as  an  approxima- 
tion. 

There  also  is  a  difference  of  opinion  concerning  the  factors  controlling  skin 
effect  in  copper  and  aluminum  wires.  These  tables  also  should  be  used  with  great 
care,  especially  for  cables  larger  than  1,000,000  cir.  mils. 

[207] 


Sec.  3  CONDUCTORS  AND  WIRE  TABLES 


/8 


7 


X'3 


W 


0     20    40    60    SO    tOO  120    /40    I&O   180    200  220  240 


Wiee 
FIG.  78. 


[208] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


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[  209  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


23 Crd.es 


0    20    40     60    80    100    120   140    160  180  200   220  240  260  280  300 


3TKANDED  CONDUCTORS 

FIG.  80. 


[210  ] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 


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[211] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


29.  STEFL  STRAND  FOR  GUYING  POLES  AND  FOR  SPAN 
WIRE.    Galvanized  or  Extra  Galvanized. 


t'iG.  82.     Seven  tteel  wires  twisted  into  a  single  strand. 


TABLE  26 
STANDARD  STEEL  STRAND 
Galvanized  or  Extra  Galvanized 

Area  in  Sq. 
Inches 

Diameter  in 
Inches 

Approximate 
Weight  per  1000 
Feet  Pounds 

Approximate 
Strength  in 
Pounds 

.1443 
.1209 
.0798 
.0639 
.0352 
.0218 
.0092 

i 

1 

510 
415 
295 
210 
125 
75 
32 

8500. 
6500. 
5000. 
3800. 
2300. 
1400. 
500. 

This  strand  is  used  chiefly  for  guying  poles  and  for  supporting 
trolley  wire. 

For  overhead  catenary  construction  suspending  trolley  wire,  the 
special  grades  of  strand  are  considered  preferable  because  they  possess 
greater  strength  and  toughness. 

30.  EXTRA  GALVANIZED  SPECIAL  STRANDS. 


FIG.  83.     Seven  steel  wires  twisted  into  a  single  strand. 

Three  special  grades  of  Extra  Galvanized  Strand  are  manufac- 
tured. 

Extra  Galvanized  Siemens-Martin  Strand.'1 

Extra  Galvanized  High  Strength  (crucible  steel)  Strand. 

Extra  Galvanized  Extra  High  Strength  (plow  steel)  Strand. 

Strands  of  all  three  grades  are  composed  of  seven  wires  each,  and 
are  galvanized. 

[212] 


CONDUCTORS  AND  WIRE  TABLES 


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CONDUCTORS  AND  WIRE  TABLES 


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CONDUCTORS  AND  WIRE  TABLES 


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CONDUCTORS  AND  WIRE  TABLES 


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[  221  ] 


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CONDUCTORS  AND  WIRE  TABLES 


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[  222  ] 


CONDUCTORS  AND  WIRE  TABLES 


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[  223  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


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[  224  ] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 


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[225] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


TABLE  39 

CAPACITY     SOLID  CONDUCTORS 

Microfarads  per  1000  Feet  of  Circuit-Formed  by  Two  Aerial  Wires 

(2000  Feet  of  Wire) 

Inter- 

SIZE  OP  WIRE—  B.  &  S.  GAUGE 

axial 

Distance, 
Inches 

0000 

000 

00 

0 

1 

2 

3 

4 

5 

6 

SA 

.14710 

.03160 

.01812 

.01303 

.01030 

.00861 

.00743 

Yz 

.05270 

.02315 

.01531 

.01156 

.00941 

.00800 

.00699 

.00622 

.00563 

.00515 

% 

.01038 

.00864 

.00746 

.00659 

.00591 

.00539 

.00495 

.00458 

.00427 

.00401 

1 

.00701 

.00625 

.00564 

.00516 

.00476 

.00443 

.00414 

.00389 

.00367 

.00349 

2 

.00415 

.00390 

.00368 

.00349 

.00332 

.00317 

.00302 

.00290 

.00278 

.00267 

3 

.00340 

.00324 

.00307 

.00296 

.00284 

.00273 

.00263 

.00253 

.00244 

.00236 

4 

.00303 

.00290 

.00279 

.00268 

.00258 

.00249 

.00240 

.00232 

.00225 

.00218 

5 

.00279 

.00268 

.00258 

.00249 

.00241 

.00233 

.00226 

.00219 

.00212 

.00206 

6 

.00263 

.00253 

00244 

.00236 

.00229 

.00222 

.00215 

.00208 

.00203 

.00197 

7 

.00250 

.00242 

00234 

.00226 

.00219 

.00213 

.00207 

.00201 

.00195 

.00190 

8 

.00240 

.00232 

00225 

.00218 

.00212 

.00206 

.00200 

.00195 

.00190 

.00185 

9 

.00232 

.00225 

00218 

.00212 

.00206 

.00200 

.00195 

.00190 

.00185 

.00180 

10 

.00226 

.00219 

00212 

.00206 

.00201 

.00195 

.00190 

.00185 

.00181 

.00176 

11 

.00220 

.00213 

00207 

.00202 

.00196 

.00191 

.00186 

.00181 

.00177 

.00172 

12 

.00215 

.00209 

00203 

.00197 

.00192 

.00187 

.00182 

.00178 

.00174 

.00170 

15 

.00203 

.00198 

00192 

.00187 

.00183 

.00178 

.00174 

.00170 

.00166 

.00162 

18 

.00195 

.00190 

00185 

.00180 

.00176 

.00172 

.00168 

.00164 

.00160 

.00157 

21 

.00188 

.00183 

00179 

.00174 

.00170 

.00166 

.00163 

.00159 

.00156 

.00152 

24 

.00182 

.00178 

00174 

.00170 

.00166 

.00162 

.00159 

.00155 

.00152 

.00149 

30 

.00174 

.00170 

00166 

.00162 

.00159 

.00155 

.00152 

.00149 

.00146 

.00143 

36 

.00168 

.00164 

00160 

.00157 

.00153 

.00150 

.00147 

.00144 

.00142 

.00139 

42 

.00163 

.00159 

00156 

.00152 

.00149 

.00146 

.00143 

.00141 

.00138 

.00135 

48 

.00159 

.00155 

00152 

.00149 

.00146 

.00143 

.00140 

.00138 

.00135 

.00133 

54 

.00155 

.00152 

00149 

.00146 

.00143 

.00140 

.00138 

.00135 

.00133 

.00130 

60 

.00152 

.00149 

00146 

.00143 

.00140 

.00138 

.00135 

.00133 

.00130 

.00128 

66 

.00150 

.00147 

00144 

.00141 

.00138 

.00136 

.00133 

.00131 

.00129 

.001280 

72 

.00147 

.00144 

00142 

.00139 

.00136 

.00134 

.00131 

.00129 

.00127 

.001246 

78 

.001454 

.001425 

001400 

.001371 

.001346 

.001321 

.001298 

.001275 

.001254 

.001232 

84 

.001436 

.001407 

001382 

.001355 

.001330 

.001307 

.001283 

.001261 

.001240 

.001218 

90 

.001420 

.001392 

001366 

001340 

.001316 

.001292 

.001270 

001248 

.001227 

.001207 

96 

.001403 

001377 

001352 

001326 

.001303 

.001280 

.001257 

001237 

.001216 

.001196 

102 

.001390 

.001363 

001338 

001314 

.001290 

.001268 

.001246 

001224 

.001205 

.001185 

108 

.001376 

.001351 

001327 

001302 

.001280 

.001257 

.001235 

001216 

.001195 

.001176 

114 

.001364 

.001339 

001315 

.001292 

001268 

.001247 

.001227 

001206 

.001186 

.001167 

120 

.001352 

001328 

001305 

001282 

001260 

.001238 

001217 

001197 

.001178 

.001160 

126 

.001342 

001318 

001294 

001272 

001250 

.001230 

001208 

001188 

.001170 

001152 

132 

.001332 

001308 

001285 

001262 

001241 

.001220 

001200 

001180 

.001162 

001145 

138 

.001323 

001299 

001277 

001256 

001233 

.001213 

001194 

001175 

.001156 

001137 

144 

.001315 

.001291 

001268 

001246 

001226 

.001206 

.001186 

001167 

.001148 

001130 

150 

.001305 

.001283 

001261 

001240 

001218 

.001200 

001180 

001160 

001142 

001125 

156 

.001298 

.001276 

001253 

001232 

001212 

001193 

001173 

001155 

001135 

001119 

162 

.001290 

.001269 

001246 

001228 

001206 

001185 

001167 

001149 

001130 

001113 

168 

.001283 

.001262 

001241 

001220 

001200 

001180 

001161.001142 

001125 

001108 

174 

.001277 

001255 

001233 

001213 

001193 

001174 

0011561.001138 

001120 

001104 

180 

.001270 

001248 

001228 

001207 

001187 

001169 

0011501.  001132 

001115 

001100 

[  226  ] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


TABLE  39—  Continued 

CAPACITY     SOLID  CONDUCTORS 

Microfarads  per  1000  Feet  of  Circuit  Formed  by  Two  Aerial  Wires 

(2000  Feet  of  Wire) 

Inter- 
axial 

SIZE  OF  WIRE  —  B.  &  S.  GAUGE 

Distance, 

Inches 

7 

8 

9 

10 

11 

12 

13 

14 

15 

s/s 

.00688 

.00589 

.00526 

.00493 

.00458 

.00427 

.00401 

.00377 

.00357 

8 

.00476 

.00444 

.00408 

.00389 

.00367 

.00348 

.00331 

.00315 

.00302 

% 

.00378 

.00357 

.00335 

.00323 

.00309 

.00295 

.00283 

.00272 

.00262 

i 

.00331 

.00316 

.00299 

.00289 

.00278 

.00267 

.00257 

.00248 

.00240 

2 

.00258 

.00248 

.00238 

.00232 

.00225 

.00218 

.00212 

.00205 

.00200 

3 

.00229 

.00222 

.00213 

.00208 

.00202 

.00197 

.00192 

.00187 

.00182 

4 

.00212 

.00206 

.00199 

.00194 

.00190 

.00185 

.00180 

.00176 

.00171 

.  5 

.00200 

.00195 

.00189 

.00185 

.00180 

.00176 

.00172 

.00168 

.00164 

6 

.00192 

.00187 

.00181 

.00178 

.001^73 

.00169 

.00166 

.00162 

.00158 

7 

.00185 

.00181 

.00175 

.00172 

.00168 

.00164 

.00161 

.00157 

.00154 

8 

.00180 

.00176 

.00170 

.00168 

.09164 

.00160 

.00157 

.00153 

.00150 

9 

.00176 

.00172 

.00167 

.00164 

.00160 

.00157 

.00153 

.00150 

.00147 

10 

.00172 

.00168 

.00163 

.00160 

.00157 

.00154 

.00150 

.00147 

.00144 

11 

.00169 

.00165 

.00160 

.00157 

.00154 

.00151 

.00148 

.00145 

.00142 

12,  - 

.00166 

.00162 

.00158 

.00155 

.00152 

.00149 

.00146 

.00143 

.00140 

15 

.00159 

.00156 

.00151 

.00149 

.00146 

.00143 

.00140 

.00138 

.00135 

18 

.00153 

.00150 

.00147 

.00144 

.00142 

.00139 

.00136 

.00134 

.00131 

21 

.00149 

.00146 

.00143 

.00141 

.00138 

.00135 

.00133 

.00130 

.00128 

24 

.00146 

.00143 

.00140 

.00138 

.00135 

.00132 

.00130 

.00128 

.00126 

30 

.00140 

.00138 

.00135 

.00133 

.00130 

.00128 

.00126 

.00124 

.00122 

36 

.00136 

.00134 

.00131 

.00129 

.00127 

.00125 

.00122 

.00120 

.30118 

42 

.00133 

.00131 

.00128 

.00126 

.00124 

.00122 

.00120 

.00118 

.00116 

48 

.00130 

.00128 

.00125 

.00123 

.00122 

.00120 

.00118 

.00116 

.00114 

54 

.00128 

.00126 

.00123 

.00121 

.00120 

.00118 

.00116 

.00114 

.00112 

60 

.00126 

.00124 

.00121 

.00120 

.00118 

.00116 

.00114 

.00112 

.00111 

66 

.00124 

.00122 

.00120 

.00118 

.00116 

.00114 

.001130 

.001110 

.001093 

72 

.001226 

.001205 

.001182 

.001167 

.001150 

.001130 

.001114 

.001097 

.001080 

78 

.001212 

.001191 

.001168 

.001155 

.001136 

.001119 

.001103 

.001086 

.001070 

84 

.001198 

.001178 

.001157 

.001142 

.001125 

.001108 

.001092 

.001075 

.001060 

90 

.001187 

.001168 

.001145 

.001132 

.001115 

.001098 

.001003 

.001065 

.001050 

96 

.001177 

.001158 

.001136 

.001122 

.001105 

.001088 

.001073 

.001057 

.001042 

102 

.001167 

.001148 

.001126 

.001113 

.001097 

.001080 

.001064 

.001050 

.001035 

108 

.001158 

.001139 

.001117 

.001105 

.001089 

.001073 

.001057 

.001042 

.001028 

114 

.001150 

.001131 

.001110 

.001098 

.001081 

.001065 

.001050 

.001035 

.001020 

120 

.001141 

.001123 

.001102 

.001090 

.001074 

.001058 

.001044 

.001028 

.001015 

126 

.001134 

.001115 

.001095 

.001083 

.001068 

.001052 

.001037 

.001023 

.001009 

132 

.001126 

.001110 

.001090 

.001077 

.001062 

.001046 

.001031 

.001016 

.001003 

138 

.001120 

.001104 

.001083 

.001071 

.001055 

.001040 

.001025 

.001011 

.000998 

144 

.001113 

.001097 

.001077 

.001065 

.001050 

.001035 

.001020 

.001006 

.000993 

150 

.001108 

.001092 

.001072 

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[  227  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


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[228] 


CONDUCTORS  AND  WIRE  TABLES 


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[  229  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


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[231] 


Sec.  3  CONDUCTORS  AND  WIRE  TABLES 


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[232  ] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


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[  233  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


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[234] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


gin 
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[  235] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


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[  236  ] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 


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[  237  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


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[  238  ] 


CONDUCTORS  AND  WIRE  TABjLES 


Sec.  3 


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[  239  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


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[  240  ] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


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[241] 


•*         O  O  <N  GO  Tj<  O 
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Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


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[  242  ] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 


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[243  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


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[244] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


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[  245  ] 


Sec.  3  CONDUCTORS  AND  WIRE  TABLES 


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[  246  ] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


TABLE  53 

STRANDED  ALUMINUM  WIRE  EQUAL  IN  CONDUC- 

TIVITY TO  STRANDED  COPPER  WIRE 

B.  &  S.  Gauge  or 
Circular  Mils. 

Diameter 
Barp 

Weight  per  1000  ft. 

Usual 

XT^.  .rtf 

Copper 

97% 

Aluminum 
61% 

Cable 

D.  B.  W. 

T.  B.  W. 

JNo*  Ot 
Strands 

1,000,000 

1,590,000 

1  •-- 

1,462 

1,958.4 

2,070. 

61 

950,000 

1,515,000 

Iff 

1,393 

1,860 

1,977. 

61 

900,000 

1,431,000 

III 

1,317 

1,765 

1,877. 

61 

850,000 

1,351,500 

u* 

1,243 

1,872 

1,779, 

61 

800,000 

1,272,000 

1,171 

1,581. 

1,683. 

61 

750,000 

1,192,500 

11 

1,098 

1,489. 

1,586. 

37 

700,000 

1,113,000 

Ui 

1,025 

1,396. 

1,489. 

37 

650,000 
600,000 

1,033,500 
954,000 

|X 

950 
877 

1,302. 
1,210. 

1,390. 
1,293. 

37 
37 

550,000 

874,500 

iS 

805 

1,119. 

1,197. 

37 

500,000 

795,000 

leV 

732 

1,027. 

1,100. 

37 

450,000 

715,500 

31 

658 

927 

994. 

37 

400,000 

636,000 

if 

585 

826. 

886. 

37 

350,000 

556,500 

fl 

512 

720. 

772. 

19 

300,000 

477,000 

B 

439 

614. 

657. 

19 

250,000 

397,500 

465 

508. 

544. 

19 

0000 

336,420 

310.2 

430.2 

460. 

7 

000 

266,800 

245.7 

345.7 

370. 

00 

211,950 

195 

279. 

300. 

0 

167,800 

155 

227. 

245. 

1 

133,220 

p 

122.6 

166.6 

178. 

2 

105,530 

97.2 

135.2 

144. 

3 

83,640 

21 

77 

109. 

117. 

4 

66,370 

H 

61.2 

91.2 

98. 

5 

52,630 

Ij 

48.5 

75.5 

82.5 

7 

6 

41,740 

•j 

38.5 

61.5 

67. 

7 

31.  THE  CORRECTION  FOR  THE  INTERNAL  INDUCTANCE 
OF  COPPER  CLAD  WIRE  may  be  made  by  the  aid  of  curves  given 
in  Figs.  84  to  87.  It  is  seldom  necessary  to  make  this  correction 
since  the  maximum  error  which  may  occur  is  not  greater  than  five 
percent,  but  if  it  is  desired,  the  percentage  from  the  curves  may  be 
applied  to  the  constant  factor  in  the  formula  for  inductance,  art.  29, 
Sec.  7. 


[247] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


[   248   ] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


2S  CYCLES 


7 


Z 


220000  C.M. 


issooo  C.M.  NNaf-a&era 
'86000 C.M.  7Wie£-ICof>PEK- 


200    220    240 


CLAD 

3TXANDCD  W/#£ 


FIG.  86 


[  249  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


OUV& 


[250] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


TABLE  54 

AVERAGE  TRACK  RESISTANCE 

Per  1000  Ft. 

(2  Rails  with  20"  Bonds) 

Rail  Weights 
Ibs.  per  yd. 

30  ft.  rails 

60  ft.  rails 

1-0000  bonds 

2-0000  bonds" 

1-0000  bonds 

2-0000  bonds 

45 
50 
55 

.01392 
.01268 
.01151 

.01314 
.01190 
.01072 

.01314 
.01190 
.01072 

.01274 
.01150 
.01033 

60 
65 
70 

.01085 
.01012 
.009562 

.01006 
.00934 
.00877 

.01006 
.00934 
.00877 

.009668 
.008940 
.008383 

75 
80 
85 

.009002 
.008532 
.008122 

.00822 
.007746 
.007336 

.00822 
.007746 
.007336 

.007823 
.007353 
.006943 

90 
95 
100 

.007762 
.007427 
.007132 

.006976 
.006641 
.006346 

.006976 
.00641 
.006346 

.006583 
.006248 
.005953 

32.  SPECIFICATION  FOR  GALVANIZED  STEEL  STRAND* 
M-Inch,  2300-pound  Strand 

This  strand  shall  be  composed  of  seven  No.  14  B.  W.  G.  galvanized 
steel  wires  and  shall  be  capable  of  withstanding  an  ultimate  breaking 
strain  of  not  less  than  2300  pounds. 

%-inch,  5000-pound  Strand 

This  strand  shall  be  composed  of  seven  No.  12  B.  W.  G.  galvanized 
steel  wires  and  shall  be  capable  of  withstanding  an  ultimate  break- 
ing strain  of  not  less  than  5000  pounds. 

Galvanizing.  The  wires  composing  a  strand  shall  be  galvanized 
in  accordance  with  the  National  Electric  Light  Association  standard 
specification  for  galvanizing. 

33.    SPECIFICATION    FOR    COPPER    WIRES    AND    CABLES 
WITH  WEATHERPROOF  INSULATION* 

Conductor.  The  copper  used  in  all  conductors  shall  have  a  con- 
ductivity of  ninety-eight  percent  of  pure  copper,  Matthiessen's 
standard.  Wire  to  be  soft  drawn,- having  a  tensile  strength  of  not 
less  than  34,000  pounds  per  square  -nch;  shall  be  uniform  in  quality, 
smooth,  free  from  flaws  and  splinters,  and  drawn  true  to  gauge. 


*N.  E.  L.  A.  specifications. 


[251  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


All  solid  conductors  shall  be  free  from  joints.  All  solid  conductors 
shall  be  B.  &  S.  gauge.  Stranded  conductors  shall  be  composed  of 
the  number  and  size  of  wires  called  for  in  this  specification. 

Insulation.  Over  the  copper  conductors  shall  be  laid  a  triple- 
braided  cotton  covering;  this  braiding  shall  be  closely  woven  and 
thoroughly  saturated  with  an  insulating  compound,  which  shall 
render  it  non-absorptive  of  moisture,  and  which  shall  not  drip  at  a 
temperature  lower  than  160  degrees  Fahrenheit,  nor  lose  its  elasticity 
at  o  degrees  Fahrenheit. 

The  finish  of  the  wires  and  cables  shall  present  a  smooth,  hard  and 
even  surface. 

The  finish  weight  of  the  various  sizes  shall  be  approximately  as 
named  below.  The  permissible  variation  in  the  finished  weights 
not  to  exceed  three  percent  under  or  over. 


SOLID 

Size  B   &  S. 

Weight  of 
Copper,  Lbs. 
per  1000  Feet 

Approx. 
Weight  of  In- 
sulation, Lbs. 
per  1000  Feet 

Approx.  Lbs. 
per  1000  Feet 

Finished 
Weight 
Pounds  per 
Mile 

0000 

640.5 

126 

767 

4050 

000 

508.0 

121 

629 

3320 

00 

402.8 

99 

502 

2650 

0 

319.5 

87 

407 

2150 

1 

253.3 

63 

316 

1670 

2 

200.9 

59 

260 

1370 

3 

159.3 

40 

199 

1050 

4 

126.4 

38 

164 

865 

6 

79.5 

32 

112 

500 

STRANDED 

Size 

No.  of 
Strands 

Size  of 
Each  Wire 
in  Mils. 

Weight  of 
Bare 
Cond. 
Lbs.  per 
1000  Feet 

Weight 
of  In- 
sulation 
Lbs.  per 
1000  Feet 

Lbs.  per 
1000  Feet 

Finished 
Weight 
Pounds 
per  Mile 

0000 

19 

105.5 

653 

147 

800 

4226 

000 

19 

94.1 

517 

136 

653 

3450 

00 

19 

83.7 

410 

112 

522 

2760 

0 

19 

74.6 

323 

101 

424 

2240 

1 

7 

109.3 

255 

73 

328 

1735 

34.     SPECIFICATION    FOR    BARE    HARD-DRAWN    COPPER 

WIRE* 

Material.  The  material  shall  be  of  copper  of  such  quality  and 
purity  that  when  hard  drawn  it  shall  have  the  properties  and  char- 
acteristics herein  required. 

*N.  E.  L.  A.  specifications. 

[252] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 

Shapes.  These  specifications  cover  hard-drawn  round  wire,  hard- 
drawn  cable  or  strand,  as  hereinafter  described. 

Finish.  The  wire,  in  all  shapes,  must  be  free  from  all  surface 
imperfections  not  consistent  with  the  best  commercial  practice. 

Packages.  Package  sizes  for  round  wire  and  for  cable  shall  be 
agreed  upon  in  the  placing  of  individual  orders.  The  wire  shall  be 
protected  against  damage  in  ordinary  handling  and  shipping. 

Specific  Gravity.  For  the  purpose  of  calculating  weights,  cross 
sections,  etc.,  the  specific  gravity  of  copper  shall  be  taken  as  8.90. 

Inspection.  All  testing  and  inspection  shall  be  made  at  the  place 
of  manufacture.  The  manufacturer  shall  afford  the  inspector  rep- 
resenting the  purchaser  all  reasonable  facilities  to  enable  him  to 
satisfy  himself  that  the  material  conforms  to  the  requirements  of 
these  specifications. 

Dimensions  and  Permissible  Variations,  (a)  Size  shall  be  ex- 
pressed as  a  diameter  of  the  wire  in  decimal  fractions  of  an  inch, 
using  not  more  than  three  places  of  decimals;  i.  e.,  in  mils. 

(b)  The  wire  is  expected  to  be  accurate  in  diameter;  permissible 
variations  from  nominal  diameter  shall  be: 

For  wire  0.100  inch  in  diameter  and  larger,  one  percent  over  or 
under.  For  wire  less  than  0.100  inch  in  diameter,  one  mil  over  or 
under. 

(c)  Each  coil  is  to  be  gauged  at  three  places,  one  near  each  end 
and  one  approximately  at  the  middle;   the  coil  may  be  rejected  if, 
two  points  being  within  the  accepted  limits,  the  third  point  is  off 
gauge  more  than  two  percent  in  the  case  of  wire  0.064  inch  in  diameter 
and  larger,  or  more  than  three  percent  in  the  case  of  wire  less  than 
0.064  inch  in  diameter. 

Physical  Tests.  The  wire  shall  be  so  drawn  that  its  tensile 
strength  and  the  elongation  shall  be  at  least  equal  to  the  values 
stated  in  the  following  table.  Tensile  tests  shall  be  made  upon  fair 
samples  and  the  elongation  shall  be  determined  as  the  permanent 
increase  in  length,  due  to  the  breaking  of  the  wire  in  tension, 
measured  between  bench  marks  placed  upon  the  wire  originally  10 
inches  apart.  The  fracture  shall  be  between  the  bench  marks  and 
not  closer  than  one  inch  to  either  mark.  If  by  testing  a  sample 
from  any  coil  of  wire  the  results  are  found  to  be  below  the  values 
stated  in  the  table,  tests  upon  two  additional  samples  shall  be  made, 
and  the  average  of  the  three  tests  shall  determine  acceptance  or 
rejection  of  the  coil.  For  wire  whose  nominal  diameter  is  between 
listed  sizes,  the  requirements  should  be  those  of  the  next  larger  size 
included  in  the  table. 

Electrical  conductivity  shall  be  determined  upon  fair  samples  by 
resistance  measurements,  at  a  temperature  of  20  degrees  Centigrade 
(68°  F.).  The  wire  shall  not  exceed  the  following  limits: 

For  diameters  0.460  inch  to  0.325  inch,  900.77  pounds  per  mile- 
ohm  at  20°  C. 

For  diameters  0.324  inch  to  0.040  inch,  910.15  pounds  per  mile- 
ohm  at  20°  C. 

[253] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


Gauge 
Number 

Diameter 
Inches 

Area 
Cir.  Mills 

Tensile 
Strength  Lbs. 
per  Sq.  In. 

Elongation  in 
10  Ins.,  Per 
Cent 

0000 

0.460 

211,600 

49,000 

2.7 

000 

0.410 

168,100 

51,000 

2.6 

00 

0.365 

133,200 

53,oOO 

2.4 

0 

0.325 

105,600 

54,500 

2.3 

.      1 

0.289 

83,520 

56,000 

2.1 

2 

0.258 

66,560 

57,500 

2.0 

3 

0.229 

52,440 

58,500 

1.9 

4 

0.204 

41,620 

59,500 

1.8 

5 

0.182 

33,120 

60,500 

1.7 

6 

0.162 

26,240 

61,500 

1.6 

7 

0.144 

20,740 

62,500 

1.5 

8 

0.128 

16,380 

63,400 

1.4 

9 

0.114 

12,996 

64,200 

1.3 

10 

0.102 

10,404 

64,800 

1.2 

11 

0.091 

8,281 

65,400 

1.1 

12 

0.081 

6,561 

65,700 

1.0 

13 

0.072 

5,184 

66,000 

0.9 

14 

0.064 

4,096 

66,200 

0.9 

15 

0.057 

3,249 

66,400 

0.8 

;   ^     16 

0.051 

2,601 

66,600 

0.8 

17 

0.045 

2,025 

66,800 

0.7 

18 

0.040 

1,600 

67,000 

0.7 

Hard-drawn  Copper  wire,  Cable  or  Strand 

Construction.  For  the  purposes  of  these  specifications,  standard 
cable  shall  be  that  made  of  hard-drawn  wire  laid  concentrically 
about  a  hard-drawn  wire  center.  Cable  laid  up  about  a  hemp  center 
or  about  a  soft  wire  core  is  to  be  subject  to  special  specifications  to 
be  agreed  upon  in  individual  cases. 

Wire.  The  wire  entering  into  the  construction  of  stranded  cable 
shall,  before  stranding,  meet  all  the  requirements  of  round  wire, 
hereinbefore  stated. 

Physical  Tests.  The  tensile  strength  of  stranded  cable  shall  be 
at  least  90  percent  of  the  total  strength  required  of  the  wires  form- 
ing the  cable. 

Brazes.  Brazes  made  in  accordance  with  the  best  commercial 
practice  will  be  permitted  in  wire  entering  into  cable;  but  no  two 
brazes  in  wire  in  the  cable  may  be  closer  together  than  fifty  feet. 

Lay.  The  pitch  of  a  standard  cable  shall  be  not  less  than  12  nor 
more  than  16  diameters  of  the  cable.  The  cable  shall  be  laid  left 
handed  or  right  handed,  as  shall  be  agreed  upon  in  the  placing  of 
the  individual  orders. 

35.     SPECIFICATION     FOR    HARD-DRAWN     COPPER-CLAD 

STEEL  WIRE* 

Material.  1.  The  material  shall  be  composed  of  a  steel  core  with 
a  copper  coat  permanently  welded  thereto  through  intervening 

*N.  E.  L.  A.  specifications. 

[  254  ]  . 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 

layers  of  copper-iron  alloys,  and  of  such  quality  and  purity  that 
when  drawn  hard  it  shall  have  the  properties  and  characteristics 
herein  required. 

Shapes.  2.  These  specifications  cover  hard-drawn  copper-clad 
wire,  as  hereinafter  described. 

Finish.  3.  The  wire  in  all  shapes  shall  be  free  from  all  surface 
imperfections  not  consistent  with  the  best  commercial  practice. 

Packages.  4.  (a)  Package  forms  for  round  wire  shall  be  agreed 
upon  in  the  placing  of  individual  orders. 

(b)  Each  coil  of  wire  shall  be  burlapped  for  protection  against 
damage  in*  ordinary  handling  and  shipping,  and  shall  have  the  gauge 
of  the  wire,  weight,  etc.,  approximate  length  of  wire  in  coil,  marked 
on  two  tags,  one  of  which  shall  be  attached  to  the  coil  inside  and  the 
other  on  the  wrapping. 

Inspection.  5.  (a)  All  testing  and  inspection  shall  be  made  at 
the  place  of  manufacture.  The  manufacturer  shall  afford  the  in- 
spector representing  the  purchaser  all  reasonable  facilities  to  enable 
him  to  satisfy  himself  that  the  material  conforms  to  the  require- 
ments of  these  specifications. 

(b)  On  orders  where  no  inspection  is  to  be  made,  the  manufacturer 
shall  test  ten  percent  (10%)  of  all  coils  for  breaking  weight  and 
conductivity,  and  in  the  event  of  their  conforming  with  the  values 
stated  in  the  following  tables,  the  material  shall  be  accepted.     A 
copy  of  these  tests  shall  be  furnished  when  requested. 

(c)  All  orders  shall  state  whether  or  not  inspection  is  to  be  made. 
Test  of  Weld.    6.  The  wire  when  broken  by  torsion  shall  show  no 

separation  of  the  copper  from  the  steel. 

The  wire  when  broken  by  repeated  bending  shall  show  no  separa- 
tion of  the  copper  from  the  steel. 

The  wire  when  heated  to  a  dull  red  and  quenched  in  iced  water 
shall  show  no  separation  of  the  copper  from  the  steel. 

Alloy  Film.  7.  When  properly  polished  and  etched  the  alloy 
film  shall  be  distinctly  visible  under  the  microscope. 

Dimensions  and  Permissible  Variations.  8.  (a)  Size  shall  be 
expressed  as  the  diameter  of  the  wire  in  decimal  fractions  of  an  inch, 
using  not  more  than  three  places  of  decimals,  i.  e.,  in  mils. 

(b)  The  wire  is  expected  to  be  accurate  in  diameter;  permissible 
variations  from  nominal  diameter  shall  be: 

For  wire  0.200  inches  and  larger  in  diameter,  one  percent  (1%) 
over  or  under. 

For  wire  0.200  to  0. 100  inches  in  diameter,  one  and  one-half  per- 
cent (1^%)  over  or  under. 

(c)  Each  coil  is  to  be  gauged  at  three  places,  one  near  each  end 
and  one  approximately  at  the  middle;   the  coil  may  be  rejected  if, 
two  points  being  within  the  accepted  limits,  the  third  point  is  off 
gauge  more  than  two  percent  (2%)  in  the  case  of  wire  0.064^  inches 
in  diameter  and  larger;   or  more  than  three  percent  (3%) 'in  the 
case  of  wire  less  than  0.064  inches  in  diameter. 

[255] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


Physical  Tests — Breaking  Weight.  9.  The  wire  shall  be  so  drawn 
that  the  breaking  weight  of  ninety  percent  (90%)  of  the  coils  tested 
shall  be  at  least  equal  to  the  values  stated  in  the  following  table, 
and  the  remaining  ten  percent  (10%)  of  the  coils  shall  not  be  more 
than  five  percent  (5%)  below  these  values. 

Tensile  tests  shall  be  made  upon  fair  samples. 

If  upon  testing  a  sample  from  any  coil  of  wire  the  results  are 
found  to  be  below  the  values  stated,  tests  upon  two  additional 
samples  shall  be  made  and  the  average  of  the  three  tests  shall  de- 
termine the  acceptance  or  rejection  of  the  coil. 


B.  &  S.  Gauge 

Diameter  in  Inches 

Breaking  Weight 

0000 
000 
00 
0 

0.460 
0.410 
0.365 
0.325 

10,000 
8,300 
6,850 
5,700 

1 

2 
3 
4 

0.289 
0.258 
0.229 
0.204 

4,800 
4,000 
3,200 
2,600 

5 
6 

7 
8« 

0.182 
0.162 
0.144 
0.128 

2,200 
1,800 
1,450 
1,200 

9 
10 

0.114 
0.102 

975 
800 

TINNED  WIRE.  The  breaking  weight  of  tinned  wire  shall  be 
taken  at  ninety  percent  (90%)  of  the  values  given  above. 

Electrical  Conductivity.  Electrical  conductivity  should  be  de- 
termined upon  fair  samples  by  resistance  measurements  at  a  tem- 
perature of  60  degrees  Fahrenheit. 

The  wire  shall  not  exceed  the  following  limits: 

(a)  Forty  percent  (40%)  of  the  conductivity  of  the  same  size 
copper  wire.     A  variation  of  five  percent  below  this  is  allowable, 
i.  e.,  the  conductivity  of  any  coil  may  be  as  low  as  thirty-five  percent 
of  that  of  the  same  size  copper  wire. 

(b)  If  upon  testing  a  sample  from  any  coil  of  wire  the  results  are 
found  to  be  bekny  the  values  stated,  the  manufacturer  reserves  the 
right  to  cut  back  into  the  coil;  the  result  of  this  test  shall  determine 
the  acceptance  or  rejection  of  the  coil. 

INSULATED  WIRE.  All  wire  to  be  insulated  must  be  inspected 
at  the  place  of  manufacture  for  mechanical  and  electrical  tests 
before  insulation,  the  inspector  sealing  all  coils  accepted.  This 
inspection  of  the  conductor  to  be  final;  further  inspection  to  be 
made  on  the  insulation  only. 

[  256  ] 


CONDUCTORS  AND  WIRE  TABLES 


Sec.  3 


36.     SPECIFICATION  FOR  ALUMINUM  WIRES  AND  CABLES, 
WEATHERPROOF  INSULATION*. 

Conductor.  Aluminum  used  in  all  conductors  shall  have  a  con- 
ductivity of  sixty-two  percent  of  pure  copper,  Matthiessen's  stand- 
ard; shall  have  tensile  strength  of  not  less  than  20,000  pounds  per 
square  inch;  shall  be  uniform  in  quality,  smooth,  free  from  flaws 
and  splinters,  and  drawn  true  to  gauge. 

Conductors  shall  be  composed  of  the  number  of  strands  of  wire 
called  for  in  this  specification. 

Each  length  of  stranded  conductor  shall  be  composed  of  wires 
without  joint. 

Insulation.  Over  the  aluminum  conductors  shall  be  laid  a  triple- 
braided  jute  or  cotton  covering.  This  braiding  shall  be  closely 
woven  and  thoroughly  saturated  with  an  insulating  compound  which 
will  render  it  non-absorptive  of  moisture,  and  which  should  not  drip 
at  a  temperature  lower  than  160  degrees  Fahrenheit,  nor  lose  its 
elasticity  at  0  degrees  Fahrenheit. 

The  finish  of  the  covering  shall  present  a  smooth,  hard  and  even 
surface. 

The  finished  weight  of  the  various  sizes  shall  be  approximately  as 
named  below.  The  permissible  variation  in  the  finished  weights 
not  to  exceed  three  percent  under  or  over. 


Aluminum 
Cir.  mils. 

Copper 
Equiv. 

No.  of 
Wires 

Wt.  of 
Bare 
Aluminum 
Pounds 
per  1000 

T?Q£»f 

Approx. 
Wt.  of 
Triple 
Braid  In- 
sulation 
Lbs.  per 

Approx. 
Finished 
Weight 
Lbs.  per 
1000  ft. 

Standard 
Length  of 
Finished 
Cable 
Feet 

X1  66  1 

1000ft. 

336,420 

0000 

7 

310.2 

150 

460 

5060 

266,800 

000 

7 

245.7 

124 

390 

3190 

211,950 

00 

7 

195.0 

115 

300 

4020 

167,800 

0 

7 

155.0 

90 

245 

5060 

133,220 

1 

7 

122.6 

55 

178 

3200 

105,530 

2 

7 

97.2 

47 

144 

4040 

83,642 

2 

7 

77.0 

40 

117 

2535 

66,370 

4 

7 

61.2 

37 

98 

3185 

37.     SPECIFICATION  FOR  BARE  ALUMINUM  WIRE* 

Material  and  Construction.  All  material  used  in  these  cables 
shall  be  of  the  best  grade  of  commercially  pure  aluminum.  It  shall 
consist  of  strands  laid  up  to  form  a  concentric  cable,  the  lay  of  the 
strands  being  as  long  as  possible  consistent  with  making  mechanically 
good  cable,  in  order  to  keep  the  increase  of  resistance  due  to  strand- 
ing as  low  as  possible. 


*N.  E.  L.  A.  specifications. 


9 


[  257  ] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


Strands.  Each  strand  used  in  the  cable  shall  be  approximately 
round  and  true  to  the  calculated  diameter  within  one  percent. 

Conductivity.  The  average  conductivity  of  the  finished  strands 
of  the  cable  shall  be  not  less  than  sixty-one  percent  in  the  Matthies- 
sen's  standard  scale,  as  determined  by  test  of  the  individual  strands 
upon  a  standard  conductivity  bridge. 

Tensile  Strength.  "The  tensile  strength  of  the  aluminum  shall 
not  be  less  than  23,000  pounds  per  square  inch  nor  more  than  30,000 
pounds  per  square  inch,  as  determined  by  tests  upon  individual 
strands  in  a  standard  tensile  testing  machine." 

Weight  and  Stranding.  The  weight  and  area  per  mile  of  bare 
cable  shall  not  vary  more  than  two  percent  from  the  following 
table. 

"The  following  table  shows  the  usual  method  of  stranding 
aluminum  conductors.  Variations  from  this  standard  stranding 
are  permissible  where  the  conditions  make  such  variation  advis- 
able." 


Aluminum  Conductor  Cir. 
Mils. 

Lbs.  per  M.  Feet 

No.  of  Strands 

66,370 

61.2 

83,642 

77. 

105,530 

97.2 

133,220 

122.6 

167,800 

155. 

211,950 

195. 

266,800 

245.7 

336,420 

310.2 

397,500 

365. 

19 

477,000 

439. 

19 

556,500 

512. 

19 

636,000 

585. 

19 

715,500 

658. 

37 

795,000 

732. 

37 

874,500 

805. 

37 

954,000 

877. 

37 

Inspection  and  Tests.  The  purchaser  shall  have  the  privilege  of 
inspecting  the  wire  called  for  on  orders,  and  notification  shall  be 
given  at  least  five  days  prior  to  the  time  that  the  material  will  be 
ready  for  inspection,  so  that  his  representative  may  be  present. 

The  manufacturers  are  to  supply  the  apparatus  necessary  to 
carry  out  all  tests,  free  of  cost  to  the  purchaser.  The  tests  are  to 
be  made  at  one  place,  and  are  to  be  to  the  satisfaction  of  the  pur- 
chaser's representative. 

Connectors.  The  manufacturer  shall  furnish  the  necessary  con- 
nectors of  a  type  to  be  approved  by  the  purchaser. 

[258] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 

38.    SPECIFICATION  FOR  RUBBER  INSULATED  TREE  WIRE 

BRAIDED* 

Conductor.  The  conductors  used  shall  consist  of  soft-drawn 
copper  wire,  with  a  conductivity  not  less  than  ninety-eight  percent 
of  pure  copper,  Matthiessen's  standard,  and  a  tensile  strength  of 
not  less  than  34,000  pounds  per  square  inch. 

Conductors  of  sizes  up  to  and  including  0  B.  &  S.  may  consist  of 
solid  or  stranded  wire.  Conductors  of  sizes  over  0  B.  &  S.  shall 
consist  of  stranded  cable. 

All  wires  shall  be  thoroughly  tinned. 

Insulation  and  Covering.  The  wire  or  cable  shall  be  covered  with 
a  wall  of  insulation  containing  not  less  than  thirty  percent  best 
Para  rubber,  free  from  substitutes  and  reclaimed  rubber. 

The  thickness  of  the  rubber  insulating  wall  shall  not  be  less  than 
the  following: 

No.  6  solid /o-  inch 

No.  4     "    

No.  2     "    

No.  1     "    

No.O     "    

No.  00  stranded 

No.  000      "        

No.  0000  "          

The  rubber  insulating  wall  shall  be  covered  with  a  drill  tape,  well 
filled  with  rubber,  and  with  a  double  braided  cotton  covering.  This 
braided  covering  shall  be  closely  woven  and  thoroughly  saturated 
with  an  insulating  compound  which  shall  render  it  non-absorptive 
of  moisture,  and  which  shall  not  drip  at  a  lower  temperature  than 
160  degrees  Fahrenheit,  nor  lose  its  elasticity  at  0  degrees  Fahren- 
heit. The  braided  covering  shall  be  thoroughly  slicked  down,  so 
that  the  complete  wire  or  cable  shall  present  a  smooth,  hard  and  even 
surface. 

39.    SPECIFICATION  FOR  CIRCULAR  LOOM-COVERED 
TREE  WIRE  NO.  6— NO.  4— No.  2* 

General  Description.  The  insulation  shall  adhere  strongly  to 
and  have  the  same  thickness  of  wall  at  all  points  from  the  conductor. 

The  covering  shall  consist  of  a  double  wrap  of  tape,  over  which 
shall  be  placed  a  tightly  woven  cotton  yarn  thoroughly  treated  with  a 
preservative  compound  containing  powdered  mica. 

Conductor.  The  conductor  shall  be  of  soft-drawn  Lake  Superior 
copper,  having  a  conductivity  of  not  less  than  ninety-eight  percent 
(98%)  Matthiessen's  standard,  and  shall  be  thoroughly  tinned. 
The  conductors  No.  6,  No.  4  and  No.  2  shall  be  solid  American  wire 
gauge. 

Tinning.  All  conductors  shall  be  thoroughly  and  evenly  coated 
with  pure  tin. 

*  N.  E.  L.  A.  specifications. 

[259] 


Sec.  3 


CONDUCTORS  AND  WIRE  TABLES 


Insulation.  The  insulating  wall  shall  consist  of  a  vulcanized 
rubber  compound  of  not  less  than  thirty  percent  by  weight  of  dry, 
"fine,  up-river"  Para  gum,  free  from  reclaimed  rubber,  shoddy  or 
rubber  substitutes,  compounded  with  from  two  to  three  percent  by 
weight  of  sulphur,  not  more  than  three  percent  of  solid  waxy  hydro- 
carbons, such  as  ozokerite  or  paraffine,  and  with  dry,  inorganic 
mineral  matter  only  as  a  matrix.  The  amount  of  extractive  matter 
contained  in  the  vulcanized  compound,  as  shown  by  chemical 
analysis,  shall  not  exceed  five  percent,  of  which  not  more  than  two 
percent  shall  be  resinous  matter  and  not  more  than  three  percent 
shall  be  waxy  hydrocarbons. 

Mechanical.  Test  pieces  cut  from  the  insulating  wall  must  stand 
stretching  not  less  than  ten  (10)  successive  times  to  two  and  one- 
half  times  their  original  length  before  breaking.  The  portion 
stretched  shall  then  return  within  one  minute  to  a  length  not  ex- 
ceeding 125  per  cent  of  its  original  length,  and  a  similar  sample 
shall  be  stretched  to  three  and  one-half  times  its  original  length 
without  sign  of  flaw  or  fracture. 

Electrical.  Each  and  every  length  of  conductor  shall  comply 
with  the  following  table : 


Megohms  per  Mile 
at  60*  F. 

Wall  of  In- 
sulation (with- 
out covering) 

Outside 
Diameter 
OverAll 

Voltage 
Test  (at 
Factory) 

No.  6  2500 
No.  4....  2100 
No.  2....  1700 

2£/32 
2^/32 
2|/32 

.500 
.530 

.594 

5000 
4500 
4500 

Tests.  The  testa  shall  be  made  at  the  works  of  the  manufacturer, 
before  the  application  of  tape,  braid  or  other  covering. 

Tests  shall  be  made  after  at  least  36  hours'  submersion  in  water 
and  while  still  immersed.  The  insulation  test  shall  follow  the 
voltage  test,  and  be  made  with  a  battery  of  suitable  electromotive 
force,  and  the  reading  shall  be  taken  after  one  minute's  electrification. 

Tape.  The  plain  insulation  shall  be  served  with  a  double  wrap 
or  rubber-filled  cloth  tape. 

Woven  Covering.  Over  the  tape  shall  be  placed  a  covering  of 
tightly  woven  cotton  yarn,  thoroughly  impregnated  with  a  pre- 
servative compound  containing  powdered  mica.  This  shall  be 
worked  into  the  interstices  of  the  weave  and  compound,  so  as  to 
prevent  the  "flaking  off"  of  the  mica  surface. 

Tests.  The  purchaser  shall  be  allowed  the  privilege  of  sending 
a  representative  to  the  works  of  the  manufacturer,  who  shall  be 
afforded  all  necessary  facilities  to  make  the  electrical  and  mechanical 
tests,  and  also  assure  himself  that  the  specifications  are  being  properly 
complied  with. 

[260] 


CONDUCTORS  AND  WIRE  TABLES  Sec.  3 


BIBLIOGRAPHY 

Publications  of  Various  Manufacturers. 

General  Electric  Review,  1909. 

Foster's  Electrical  Engineers'  Pocket  Book. 

N.  E.  L.  A.  Report  of  Committee  on  Overhead  Line  Construction, 

1911. 
U.  S.  Bureau  of  Standards,  No.  31. 


SECTION  4 

CROSS-ARMS,  PINS  AND  POLE  LINE 
HARDWARE 


* 


SECTION  4 

CROSS-ARMS,  PINS  AND  POLE  LINE  HARDWARE 


TABLE  OF  CONTENTS 

ARTICLE 

Cross-arms 1 

Wood  Cross-arms  , 2 

Specifications  for  Untreated  Cross-arms 3 

Specifications  for  Creosoted  Pine  Cross-arms 4 

Steel  Cross-arms 5 

Patent  Cross-arms 6 

Pins 7 

Standard  Pin  Threading 8 

Specification  for  Wood  Insulator  Pins 9 

Combination  Wood  and  Metal  Pins 10 

Metal  Pins 11 

Screw  Type 12 

Cemented  Type 13 

Attaching  Pins  to  Cross-arms 14 

Line  Hardware 15 

(a)  Cross-arm  Braces. 
Specification  for  Cross-arm  Braces. 

(b)  Cross-arm  Bolts,  Carriage  Bolts,  Lag  Screw  and  Washers. 
Specification  for  Cross-arm  Bolts,  Carriage  Bolts,    Lag 

Screws  and  Washers. 

(c)  Pole  Steps. 
Specification  for  Pole  Steps. 

<d)    Guy  Rods. 

Specification  for  Guy  Rods. 
(e)    Patent  Guy  Anchors. 


f  265  ] 


1.  CROSS-ARMS  are  generally  of  wood  or  steel,  although  some 
attempt  has  been  made  to  manufacture  concrete  arms,  but  their 
use  has  been  so  limited  and  the  available  data  so  meager  that  no 
information  on  concrete  cross-arms  can  be  given. 

2.  WOOD    CROSS-ARMS  are  usually  of  long  leaf  yellow  pine, 
Douglas  fir,  short  leaf  yellow  pine  or  Norway  pine,  although  other 
woods  such  as  oak,  spruce,  cedar,  white  pine,  loblolly  pine  and  cypress 
have  been  used  to  some  extent. 

Standard  specifications  for  wood  cross-arms  have  been  approved 
by  the  National  Electric  Light  Association  covering  two  (2),  four  (4), 


I/GH  Bo^r  #MC~~J^- -n  — *f—  n 

I  i  TT|  -4   j 


FIG.  88 — Standard  cross-arms 

six  (6)  and  eight  (8)  pin  arms,  (Fig.  88)  made  from  Norway  pine, 
yellow  pine,  cypress  or  Douglas  fir,  and  are  as  follows: 

3.  SPECIFICATION  FOR  UNTREATED  CROSS-ARMS.* 

These  specifications  cover  two,  four,  six,  and  eight  pin  painted 
cross-arms  made  of  Norway  pine,  yellow  pine,  cypress  or  Douglas  fir. 

Norway  pine  is  understood  to  cover  what  is  also  known  as  red 
pine. 

*  Standard  National  Electric  Light  Association  Specification. 
[267] 


Sec.  4  CROSS-ARMS,  PINS,  ETC. 

Yellow  pine  is  understood  to  cover  what  is  commonly  known  as 
Longleaf  pine.  It  is  understood  that  the  term  is  descriptive  of 
quality  rather  than  of  botanical  species. 

Douglas  fir  is  understood  to  cover  the  timber  known  likewise  as 
yellow  fir,  red  fir,  western  fir,  Washington  fir,  Oregon  or  Puget 
Sound  fir  or  pine,  Northwest  and  West  Coast  fir. 

Cypress  is  understood  to  cover  the  timber  known  as  red  cypress. 

GENERAL 

The  specifications  and  drawing  Fig.  88  are  intended  to  include 
all  instructions  necessary  for  the  manufacturer  to  guide  him  in  his 
work.  They  are  intended  to  co-operate  with  and  supplement  each 
other,  so  that  any  details  indicated  in  one  and  not  in  the  other  shall 
be  executed  the  same  as  if  indicated  in  both. 

WORKMANSHIP 

All  material  and  workmanship,  unless  otherwise  specified,  shall 
be  of  the  best  commercial  grade. 

MATERIAL 

Norway  Pine  Cross-arms.  All  Norway  pine  cross-arms  shall  be 
made  of  thoroughly  air-dried  or  kiln-dried,  straight-grained  Norway 
pine. 

Yellow  Pine  Cross-arms.  All  yellow  pine  cross-arms  shall  be  made 
of  thoroughly  air-dried,  or  kiln-dried,  straight-grained  long-leaf 
yellow  pine. 

Cypress  Cross-arms.  All  cypress  cross-arms  shall  be  made  of 
thoroughly  air-dried  or  kiln-dried,  straight-grained  cypress. 

Fir  Cross-arms.  All  fir  cross-arms  shall  be  made  of  thoroughly 
air-dried  or  kiln-dried,  straight-grained  Douglas  fir. 

DIMENSIONS 

Cross-arms  shall  be  of  the  style  and  dimensions  shown  in  Fig.  88. 
Figures  upon  the  drawing  shall  be  followed  in  preference  to  scale 
measurements. 

QUALITY 

Pith  Heart.     Cypress  cross-arms  shall  be  free  from  pith  heart. 

Sapwood.  Cypress  cross-arms  shall  be  free  from  sap  wood. 
Norway  pine,  yellow  pine,  and  Douglas  fir  cross-arms  may  contain 
sap  wood,  provided  it  is  clear  and  does  not  form  over  fifteen  (15) 
percent  of  the  cross-section  of  the  cross-arm.  Cross-arms  shall  be 
shaped  so  that  the  sapwood  shall  be  on  the  top  or  the  sides  of  the 
cross-arms. 

Grain.  All  cross-arms  shall  be  reasonably  straight  grained.  The 
grain  shall  not  depart  from  parallelism  to  any  edge  of  the  cross-arm 
by  an  amount  greater  than  one  (1)  inch  to  three  (3)  feet  length  of 
cross-arm.  All  cross-arms  shall  be  out  of  wind. 

[268  ] 


CROSS-ARMS,  PINS,  ETC.  Sec.  4 

Pitch  Pockets.  All  cross-arms  shall  be  free  from  pitch  pockets 
exceeding  five  (5)  inches  in  length  and  one-quarter  (j£)  of  an  inch 
in  width,  and  from  all  pitch  pockets  which  enter  the  pin  or  bolt 
holes  on  the  top  or  sides  of  the  cross-arm. 

Knots.     All  cross-arms  shall  be  free  from  loose  or  unsound  knots. 

Eight  (8)  pin  cross-arms  shall  be  free  from  knots  at  the  third, 
fourth,  fifth  and  sixth  pin  holes,  and  the  bolt  holes;  six  (6)  pin 
cross-arms  shall  be  free  from  knots  at  the  two  middle  pin  holes  and 
the  bolt  holes. 

Eight  (8)  pin  cross-arms  may  have  sound  knots  not  over  three- 
quarter  inch  in  diameter  between  the  third  and  fourth  pin  holes, 
the  fourth  pin  hole  and  the  middle  bolt  hole,  the  middle  bolt  hole 
and  the  fifth  pin  hole,  and  the  fifth  and  sixth  pin  holes;  six  (6)  pin 
cross-arms  may  have  sound  knots  not  over  three-quarter  inch  in 
diameter  between  the  middle  bolt  hole  and  the  middle  pin  holes. 

Eight  (8)  pin  cross-arms  may  contain  sound  knots,  as  specified 
below,  outside  the  third  and  sixth  pin  holes;  and  six  pin  arms  out- 
side of  the  middle  pin  holes.  Such  knots  may  gradually  increase  in 
size  from  three-quarter  inch  near  the  above-mentioned  pin  holes  to 
one-half  the  cross-section  of  the  arm  at  the  ends. 

Wane.  All  cross-arms  shall  be  free  from  wane. 

Shakes.  All  cross-arms  shall  be  free  from  through  shakes,  and 
from  other  shakes  or  checks  exceeding  three  (3)  inches  in  length. 

Warp.  A  straight  edge  laid  lengthwise  on  the  concave  side  of 
an  eight  (8)  pin  or  a  six  (6)  pin  cross-arm  shall  not  show  an  offset 
greater  than  one  (1)  inch  on  the  eight  (8)  pin  cross-arm  and  greater 
than  three-quarters  (%)  of  an  inch  on  the  six-pin  cross-arm. 
No  cross-arm  shall  be  twisted  or  bent  in  more  than  one  direction  or 
bent  in  one  direction  on  edge. 

Loose  Heart.     All  cross-arms  shall  be  free  from  loose  hearts. 

Rot.     All  cross-arms  shall  be  free  from  rot,  dote  or  red  heart. 

Worm  Holes.     All  cross-arms  shall  be  free  from  worm  holes. 


INSPECTION 

All  cross-arms  shall  be  inspected  for  dimensions  and  defects 
outlined  under  "Quality"  before  painting. 

The  spacing  of  the  pin  and  bolt  holes  shall  be  within  the  limits 
shown  in  Fig.  88. 

Pin  and  bolt  holes  shall  be  tested  with  steel  gauges  and  shall  take 
gauges  as  follows: 

Pin  holes  l>^-inch   gauge  without  forcing  but  not  a 

1  ^§-inch  gauge. 

Middle  bolt  hole    %-inch  gauge,  without  forcing 
Brace  bolt  holes     %-inch  gauge,  without  forcing 

All  cross-arms  not  conforming  to  these  requirements  shall  be 
rejected. 

[269] 


Sec.  4  CROSS-ARMS,  PINS,  ETC 

The  pin  and  bolt  holes  shall  be  smooth  and  the  arms  shall  not  be 
badly  splintered  where  the  bits  have  broken  through. 

The  brace  bolt  holes  shall  not  be  drilled  through  the  pin  holes. 

STORAGE 

After  the  cross-arms  are  shaped  they  shall  be  stacked  in  cross- 
piles  on  skids  in  such  a  manner  as  to  insure  good  ventilation.  The 
stacks  shall  be  roofed  to  prevent  the  penetration  of  rain,  or  the 
direct  action  of  the  sun, 

4.  SPECIFICATION  FOR  CREOSOTED  PINE  CROSS-ARMS.* 

Material.  All  cross-arms  shall  be  made  from  sound,  straight- 
grained,  short  leaf  or  loblolly  pine. 

Quality.  All  cross-arms  shall  be  free  from  loose  or  unsound  knots 
over  three-quarters  (%)  of  an  inch  in  diameter.  They  shall  be  free 
from  loose  hearts,  rot,  dote,  red  heart,  worm  holes,  shakes  or  ex- 
cessive wane  or  pitch  pockets. 

Workmanship.  All  material  and  workmanship  shall  be  of  the 
best  commercial  grade. 

Storing.  If  the  cross-arms  are  to  be  stored  by  the  manufacturer, 
they  shall  be  so  stacked  in  cross  piles  on  skids  as  to  insure  good 
ventilation  and  shall  be  roofed  to  exclude  sun  and  rain. 

Dimensions.  All  cross-arms  shall  be  of  the  style  and  of  the 
dimensions  shown  in  drawing  (Fig.  88),  which  drawing  forms  a  part 
of  this  specification. 

Creosoting  shall  comply  with  the  specification  for  creosoting  in 
Section  9,  article  14. 

5.  STEEL  CROSS-ARMS  are  usually  of  angle  or  channel  section. 
Such  arms  have  not  been  standardized.     Their  length,  the  location 
of  the  pin  holes  and  bolt  holes  are  dependent  upon  the  conductor 
spacing,  the  conductor  arrangement  which  it  is  proposed  to  use, 
and  upon  the  method  by  which  the  arm  is  to  be  attached  to  the  pole. 

6.  SPECIAL  CROSS-ARMS  constructed  of  malleable  iron,  pipe 
fittings  and  various  steel  sections  are  available,  two  of  which  are 
illustrated  in  Figs.  89  and  90.     Such  cross-arms  are  manufactured 
for  different  conductor  separations. 

7.  PINS  may  be  divided  into  three  general  classes: 

(a)  All  wood  pins; 

(b)  Combinations  of  steel,  wood  and  porcelain  pins; 

(c)  All  metal  pins. 

Wood,  as  a  structural  material  for  use  in  supporting  line  insulators, 
has  for  many  years  been  regarded  as  desirable.  It  is  cheap,  easily 
fabricated  and  in  some  slight  degree  adds  to  the  insulator  strength. 

*From  1911  Report  of  the  Committee  for  the  Preservative  Treatment  of 
Wood  Poles  and  Cross-arms. 

[  270] 


CROSS-ARMS,  PINS,  ETC. 


Sec.  4 


A  properly  impregnated  pin  of  generous  design  is  generally  satis- 
factory, except  when  Used  on  higher  potential  systems.  Thte  fault 
with  wood  pins  lies  in  the  danger  of  burning  or  digesting  of  that 
portion  of  the  pin  adjacent  to  the  insulator.  At  the  threaded  per- 


tion,  the  wood  pin  is  of  smallest  cross-section,  and  being  thoroughly 
dry  at  this  point,  the  resistance  to  leakage  or  capacity  current  flow 
is  greatest.  Also  the  electrostatic  flux  density  is  greatest  at  the 

[271] 


Sec.  4 


CROSS-ARMS,  PINS,  ETC. 


point  of  least  cross-section,  so  that  burning  or  digesting  of  the  pin 
may  occur.  Metal  pins  entirely  relieve  the  burning  and  digesting 
difficulty  and  also  provide  greater  mechanical  strength. 

In  general,  wood  pins  used  in  connection  with  insulators  of  very 
high  factors  of  safety,  in  climates  not  affected  by  salt  fogs  or  chemical 
fumes  are  reasonably  satisfactory. 

Solid  steel  or  iron  pins  are  not  as  desirable  as  those  pins  which 
include  some  form  of  separable  thimble,  that  can  be  economically 
and  properly  cemented  into  the  insulator  at  the  factory  and  in  turn 
screwed  on  to  the  pin  body  erected  on  the  poles  or  towers.  Probably 
the  greatest  benefit  of  this  iorm  of  construction  is  the  ease  with 
which  broken  insulators  can  be  replaced. 

8.  STANDARD  PIN  THREADING.  The  standard  pitch  for 
pin  and  pinhole  threading  is  4  threads  per  inch  and  the  standard 
diameters  are  1"  (standard  pinhole)  and  1%"  (large  pinhole). 
These  diameters  are  the  extreme  diameters  at  the  top  of  the  pin 
and  at  the  bottom  of  the  pinhole  as  illustrated  (Fig.  91).  The 


FIG.  91. — Standard  pin  threads. 

standard  taper  for  the  diameters  of  pins  and  pinholes  is  ^  "  in- 
crease in  diameter  per  1"  in  length. 

The  National  Electric  Light  Association  standard  wood  pin  is 
illustrated  in  Fig.  92,  specifications  for  which  follow: 

9.  SPECIFICATION  FOR  WOOD  INSULATOR  PINS.* 

The  quality  of  the  materials  used  and  the  methods  of  manufacture, 
handling  and  shipment  shall  be  such  as  to  insure  for  the  finished 
pins  the  properties  and  finish  called  for  in  these  specifications.  The 
manufacturer  must  make  sure  that  all  materials  and  work  are  in 
accordance  with  the  specifications  before  the  pins  are  delivered. 
The  purchasing  company  is  to  have  the  right  to  make  such  inspections 
and  tests  as  it  may  desire,  of  the  materials  and  of  the  pins  at  any 
stage  of  the  manufacture,  such  inspections  not  to  include  the  in- 
spection of  the  processes  of  manufacture.  The  inspector  of  the 


*  Standard  National  Electri 


Light  Association  Specification. 
[272] 


CROSS-ARMS,  PINS,  ETC. 


Sec.  4 


purchasing  company  shall  have  the  power  to  reject  any  pin  which 
fails  to  satisfy  the  requirements  of  these  specifications.  Inspection 
shall  not,  however,  relieve  the  manufacturer  from  the  obligation  of 
furnishing  satisfactory  material  and  sound,  reliable  work. 

Any  unfaithful  work  or  failure  to  satisfy  the  requirements  of  these 
specifications  that  may  be  discovered  by  the  purchasing  company 
on  or  before  the  receipt  of  the  finished  pins  shall  be  corrected 


FIG.  92.— Standard  N.  E.  L.  A.  wood  pin. 

immediately  upon  the  requirement  of  the  purchasing  company,  not- 
withstanding that  it  may  have  been  overlooked  by  the  inspector. 

General.  These  specifications  cover  the  manufacture  of  standard 
locust  pins  as  ordered. 

The  drawings  and  specifications  are  intended  to  include  all  in- 

[273] 


Sec.  4  CROSS-ARMS,  PINS,  ETC. 

structions  necessary  for  the  manufacturer  to  guide  him  in  his  work. 
They  are  intended  to  co-operate  with  and  supplement  each  other, 
so  that  any  details  indicated  in  one  and  not  in  the  other  shall  be 
executed  the  same  as  if  indicated  in  both. 

Figures  upon  the  drawing  shall  be  followed  in  preference  to  scale 
measurements. 

All  material  and  workmanship,  unless  otherwise  specified  herein, 
shall  be  of  the  best  grade. 

Material.  All  pins  shall  be  made  of  sound,  straight  grained 
yellow  or  black  locust,  free  from  knots,  checks,  sapwood,  worm 
holes,  brash  wood,  cracks  or  other  defects,  except  as  hereinafter 
specified. 

Knots.  The  pins  shall  be  free  from  large,  loose  or  unsound 
knots.  Small  knots  not  over  one-eighth  (^g)  of  an  inch  in  diameter 
are  allowable  on  the  shoulder  and  on  the  lower  half  of  the  shank  of 
the  pin. 

Checks.  Small  season  checks  are  allowable  on  the  shoulder  and 
on  the  lower  half  of  the  shank  of  the  pin.  The  number  of  such 
pins  shall  not  exceed  five  (5)  percent  of  the  number  furnished. 

Sapwood.  Sapwood  is  allowable  on  the  shoulder  of  the  pin  pro- 
vided it  does  not  extend  to  the  shank 

Worm  Holes.  If  the  wood  is  otherwise  sound,  worm  holes  are 
allowable  on  the  lower  third  of  the  shank.  The  number  of  such 
pins  shall  not  exceed  five  (5)  percent  of  the  number  furnished. 

Finish.  The  grain  of  the  wood  on  all  pins  shall  be  reasonably 
parallel  to  the  axis  of  the  pin.  The  grain  through  the  center  of  the 
bottom  of  the  pin  shall  not  run  out  below  the  bottom  thread. 

Seasoned  Pins.  All  seasoned  pins  shall  have  four  (4)  threads  to 
the  inch,  and  the  dimensions  shown  on  drawing,  Fig.  92. 

The  threads  shall  be  smooth  and  of  uniform  pitch,  and  such  that 
a  standard  insulator  can  be  readily  screwed  on  to  a  standard  pin, 
until  the  end  of  the  pin  touches  the  top  of  the  insulator  and,  when  in 
this  position,  there  shall  be  no  perceptible  rocking  or  play  of  the 
insulator  on  the  pin. 

The  pins  shall  be  as  nearly  as  possible  of  a  circular  cross-section. 

Flat  surfaces  not  over  one-eighth  (}/$)  of  an  inch  in  depth  are 
allowable  on  the  shoulders  of  the  pins;  the  number  of  such  pins 
shall  not  exceed  five  (5)  percent  of  the  number  furnished. 

Unseasoned  Pins.  Pins  manufactured  from  green  or  partially 
seasoned  wood  shall,  when  seasoned,  conform  to  the  requirements 
above  specified  for  seasoned  pins. 

10.  COMBINATION  WOOD,  PORCELAIN  AND  METAL  PINS, 

are  usually  made  by  using  a  wood  top,  a  wood  and  porcelain  top,  or 
a  metal  and  porcelain  top  and  a  steel  through  bolt  as  illustrated  in 
Figs.  94-95. 

11.  METAL  PINS.     The  construction  of  metal  pins  varies  in 
the  manner  in  which  the  insulator  is  attached  to  the  pin  and  the 
manner  in  which  the  pin  is  attached  to  the  crossarm.     Insulators 
may  be  attached  to  the  pin  by  either  of  two  methods: 

[274] 


CROSS-ARMS,  PINS,  ETC. 


Sec.  4 


FIQ.  93. — Wood  or  solid 
metal  pin. 


FIG.  94.— Wood,  steel,      Fia.  95.— Porcelain  base 
through  bolt  pin.  wood  top  pin. 


FIG.  96 — Clamp  pin,  solid  metal  split 
head,  with  felt  insertion. 


FIG.  97 — Wire  screw  thread, 
clamp  pin. 


F2751 


Sec.  4 


CROSS-ARMS,  PINS,  ETC. 


M, 


[276] 


CROSS-ARMS,  PINS,  ETC. 


Sec.  4 


T  277  ] 


Sec.  4  CROSS-ARMS,  PINS,  ETC. 

(a)  The  screw  type  in  which  the  insulator  is  screwed  on  to  the 
pin.     (Art.  12.) 

(b)  The  cemented  type  in  which  the  insulator  is  cemented  to  the 
pin  or  a  detachable  portion  of  the  pin.     (Art.  13.) 

12.  SCREW  TYPE.     The  designs   of  screw  threads  vary.     A 
number  of  types  are  as  follows: 

1st.  The  solid  metal  pin  (Fig.  93)  because  of  the  unequal  expansion 
and  contraction  of  the  pin  and  the  insulator,  may  cause  failure  of 
the  insulator.  When  such  pins  are  used  it  is  customary  to  wrap 
the  pin  with  a  few  layers  of  tape  thus  providing  a  cushion  to  relieve 
the  stresses. 

2nd.  The  solid  metal  pin  in  which  the  head  is  split  (Fig.  96)  and 
a  piece  of  felt  inserted,  in  order  to  relieve  the  unequal  expansion  and 
contraction  stresses. 

3rd.  The  spiral  spring  (Fig.  97)  in  which  the  stresses,  due  to  the 
unequal  expansion  and  contraction,  are  relieved  by  the  lengthening 
or  shortening  of  the  spring,  which  slowly  twists  around  in  the 
insulator. 

4th.  The  flexible  stamped  thread  (Fig.  98)  consisting  of  a  solid 
pin  on  which  is  riveted  a  steel  saw  tooth  shaped  flexible  stamping, 
which  allows  for  the  unequal  expansion  and  contraction  of  the 
insulator  and  pin.  A  flat  spring  over  the  top  of  the  solid  part  of 
the  pin  prevents  breakage  of  the  insulator  when  installing. 

13.  CEMENTED  TYPE.     Pins  to  which  insulators  are  cemented 
are  of  two  general  classes: 

(a)  Pins  to  which  the  insulator  is  directly  cemented  (Figs.  101 
and  105.) 

(b)  Pins  with  separable  thimbles,  the  thimble  only  being  cemented 
into  the  insulator.     (Figs.  99,  100,  102,  103,  104.) 

The  latter  are  the  types  generally  used,  as  the  former  necessitate 
the  removal  of  the  pin  when  changing  the  insulator. 

14.  ATTACHING    PINS    TO    CROSS-ARMS.     Pins    may    be 
attached  to  the  cross-arms  by  three  methods: 

(a)  A  driving  fit,   (Fig.  93)  in  which  the  tapered  pin  shank  is 
driven  into  a  hole  in  the  cross-arm.     This  type  is  generally  used  in 
connection  with  wood  cross-arms  and  is  usually  confined  to  all  wood 
pins.     Where  so  used,  a  nail  is  driven  through  the  cross-arm  and 
the  pin  in  order  to  secure  the  pin  in  position. 

(b)  Bolted  type  (Figs.  94,  95,  99, 100, 102, 103, 104, 105)  in  which 
the  pin  is  fastened  to  the  cross-arm  by  means  of  a  through  bolt. 

(c)  The  clamp  pin  (Figs.  96,  97,  98,  101)  in  which  the  pin  is  so 
constructed  that  the  cross-arm  is  girdled  and  the  pin  clamped  into 
position. 

15.  LINE  HARDWARE 

(a)  Cross-arm  Braces  may  be  either  of  flat  bar  or  angle  section. 
For  ordinary  distribution  work  flat  bar  braces  are  generally  used. 

F  278  1 


CROSS-ARMS,  PINS,  ETC. 


Sec.  4 


The  standard  section  of  steel  bar  braces  is  \Y±'  x  %";  the  length 
from  20"  to  32".  Angle  iron  braces  in  one  piece,  as  illustrated  in 
Fig.  106  have  been  used  to  some  extent  in  wood  pole  work.  The 
standard  National  Electric  Light  Association  28"  brace  is  illustrated 
in  Fig.  107,  specification  for  which  follow: 


FIG.  106.  Angle  iron  cross-arm  brace. 

SPECIFICATIONS  FOR  CROSS-ARM  BRACES.* 

Workmanship.  All  material  and  workmanship  shall  be  of  the 
best  grade. 

Material.  All  braces  shall  be  made  of  iron  or  mild  steel,  "Manu- 
facturers' Standard,"  galvanized  or  ^sherardized,  as  provided  in 
The  National  Electric  Light  Association  standard  specification  for 
galvanizing  or  sherardizing. 

The  holes  in  the  braces  shall  be  clear  and  free  from  superfluous 
zinc. 

Dimensions.  All  braces  shall  be  made  in  accordance  with  the 
dimensions  shown  in  drawing,  Fig.  107. 


If 


J) 


FIG.  107.  Standard  N.  E.  L.  A.    Cross-arm  brace. 

(b)  Cross-arm  Bolts,  Carriage  Bolts,  Lag  Screws  and  Washers. 

The  National  Electric  Light  Association  standard  cross-arm  bolts, 
carriage  bolts,  lag  screws  and  washers  are  illustrated  in  Fig.  96, 
specification  for  which  follows: 

SPECIFICATION  FOR  CROSS-ARM  BOLTS,  CARRIAGE  BOLTS, 
LAG  SCREWS  AND  WASHERS.* 

This  specification  covers  bolts  with  cut  thread  only,  which  must 
be  furnished  unless  specific  instructions  are  given  otherwise.  Lag 


*  Standard  National  Electric  Light  Association  Specification. 
[  279  ] 


Sec.  4 


CROSS-ARMS,  PINS,  ETC. 


CROSS-ARMS,  PINS,  ETC.  Sec.  4 

screws  can  be  furnished  with  either  fetter  or  twist  threads,  unless 
either  one  is  particularly  specified. 

The  materials  and  styles  called  for  are  intended  to  be  stock 
materials  and  sizes.  Should  the  detail  dimensions  conflict  with 
standard  sizes,  the  manufacturer  should  state  wherein  the  differ- 
ences exist,  but  in  all  cases  the  mechanical  requirements  must 
conform. 

Workmanship.  All  material  and  workmanship  specified  herein 
shall  be  of  the  best  grade. 

Material.  Cross-arm  bolts,  carriage  bolts,  lag  screws  and  washers 
shall  be  made  of  iron  or  mild  steel,  "Manufacturers'  Standard," 
and  shall  be  galvanized  or  sherardized  in  accordance  with  the 
National  Electric  Light  Association  standard  specification  for 
galvanizing  or  sherardizing. 

Dimensions.  The  dimensions  of  this  material  shall  be  in  accord- 
ance with  drawing,  Fig.  108. 

Finish.  All  bolts  must  be  free  from  badly  formed  or  otherwise 
defective  heads.  The  heads  of  the  bolts  must  be  rounded  or 
chamfered.  The  threads  must  be  full  and  clean  and  concentric  with 
the  axis  of  the  bolts. 

All  nuts  must  be  symmetrically  formed  and  must  have  the  hole 
centrally  located.  The  axis  of  the  threads  must  be  perpendicular 
to  the  face  of  the  nut.  All  nuts  must  be  an  easy  fit  for  the  bolt, 
so  that  the  nut  can  be  run  the  entire  length  of  the  thread  without 
undue  forcing  with  the  fingers. 

All  washers  must  be  symmetrically  formed  and  have  the  holes 
centrally  located. 

Bolt  heads,  nuts,  etc.,  shall  be  of  sufficient  strength  to  develop 
the  ultimate  strength  of  the  bolt  shank. 

Galvanizing.  All  galvanizing  or  sherardizing  shall  be  in  accord- 
ance with  the  National  Electric  Light  Association  standard  specifica- 
tion for  galvanizing  or  sherardizing. 

A  coating  of  zinc  shall  be  left  on  the  threads  of  the  bolts  conform- 
ing in  all  respects  with  the  said  specifications  for  galvanizing  or 
sherardizing. 

The  threads  of  the  nuts  need  not  be  galvanized. 

The  holes  in  the  washers  shall  be  clean  and  free  from  superfluous 
zinc. 

The  galvanizing  shall  not  be  chipped  off  when  washers  have  stuck 
together. 

(c)  Pole  Steps.  The  standard  National  Electric  Light  Associa- 
tion wood  pole  step  is  illustrated  in  Fig.  109,  specifications  for  which 
follow: 

SPECIFICATION  FOR  POLE  STEPS* 

Workmanship.  All  material  and  workmanship  shall  be  of  the 
best  grade. 

*  Standard  National  Electric  Light  Association  Specifications. 

[  281  1 


Sec.  4 


CROSS-ARMS,  PINS,  ETC. 


Material.  All  pole  steps  shall  be  made  of  iron  or  mild  steel, 
"Manufacturers'  Standard,"  galvanized  or  sherardized  in  accord- 
ance with  the  National  Electric  Light  Association  standard  specifica- 
tion for  galvanizing  or  sherardizing. 

Dimensions.  All  pole  steps  shall  be  made  in  accordance  with  the 
dimensions  shown  in  drawing,  Fig.  109. 

Mechanical  Requirements.  When  rigidly  held  by  the  head, 
the  pole  step  shall  be  capable  of  being  bent  through  an  angle  of 
90  degrees,  about  a  diameter  equal  to  the  diameter  of  the  pole  step, 
without  breaking. 


FIG.  109.— Standard  pole  step. 

(d)  Guy  Rods.     The  standard  National  ElectricLight  Association 
guy  rods  are  illustrated  in  Fig.  110,  specification  for  which  follows: 


SPECIFICATION  FOR  GUY  RODS* 

This  specification  covers  the  construction  of  a  standard  guy  rod. 

Workmanship.  All  material  and  workmanship  shall  be  of  the 
best  grade. 

Material.  All  guys  rods  shall  be  made  of  iron  or  mild  steel, 
"Manufacturers'  Standard,"  galvanized  or  sherardized. 

Dimensions.  All  guy  rods  shall  be  made  in  accordance  with  the 
drawing  shown  in  Fig.  110. 

Finish.  The  welded  joints  shall  be  of  the  best  workmanship, 
thoroughly  welded  without  being  overheated. 

The  threads  on  the  bolts  shall  be  full  and  clean  and  concentric 
with  the  axis  of  the  rod.  The  thread  end  of  the  rod  shall  be  rounded 
or  chamfered. 

All  nuts  shall  be  symmetrically  formed  and  shall  have  holes 
centrally  located. 

The  axis  of  the  threads  shall  be  reasonably  perpendicular  to  the 
face  of  the  nut.  All  nuts  must  be  an  easy  fit  for  the  bolt,  so  that 
the  nut  can  be  run  the  entire  length  of  the  thread  without  undue 
forcing  with  the  fingers. 

*  Standard  National  Electric  Light  Association  Specification. 
[  282  ] 


CROSS-ARMS,  PINS,  ETC. 


Sec.  4 


[  283  ] 


Sec.  4  CROSS-ARMS,  PINS,  ETC. 

All  washers  must  be  symmetrically  formed  and  have  the  holes 
centrally  located. 

Mechanical  Requirements.  The  strength  of  the  eye,  nut  and 
thread  shall  be  sufficient  to  develop  the  ultimate  strength  of  the  rod. 

Galvanizing.  All  galvanizing  or  sherardizing  shall  be  done  in 
accordance  with  the  National  Electric  Light  Association  standard 
specification  for  galvanizing  or  sherardizing.  A  coating  of  zinc 
shall  be  left  on  the  threads  of  the  rods.  The  threads  of  the  nuts 
need  not  be  galvanized. 


(e)  Patent  Guy  Anchors.     There  are  a  number  of  different  designs 
on  the  market.     Among  them  are  the  screw  type,  the  scoop  or  flat 
expanding  plate  type,  the  straight  malleable-iron  plate  deadman  and 
various  kinds  of  harpoon-like  designs. 

The  screw  type  is  set  in  the  ground  by  means  of  a  special  wrench 
and  requires  no  digging  in  its  installation. 

The  scoop  and  the  expanding  types  of  anchors  require  the  digging 
of  holes  of  small  diameter  with  an  earth  auger. 

The  expanding  types  are  placed  in  straight  auger  holes  and  then 
by  hammering  a  shoulder  or  lug  with  a  tamping  bar,  multiple  discs 
or  arms  are  projected  into  the  walls  of  the  hole. 

The  value  of  a  patent  guy  anchor  in  any  particular  soil  is  dependent 
upon  the  effective  bearing  area  that  it  possesses.  Where  guys 
supporting  excessive  strains  are  used,  the  deadman  or  anchor  log 
type  will  usually  prove  the  more  satisfactory. 

(f )  Pole  Brackets.     The  number  of  designs  of  pole  brackets  are  so 
numerous  and  their  selection  is  so  dependent  upon  the  type  of  con- 
struction adopted,  that  illustrations  or  descriptions  to  be  of  any 
value  require  considerable  space.     In  general,  such  brackets  should 
be  carefully  selected  with  respect  to  strength  and  stability  of  con- 
struction, and  should  be  galvanized  or  sherardized  in  accordance 
with    the    National   Electric   Light  Association  specification  for 
galvanizing  or  sherardizing. 


BIBLIOGRAPHY 

N.  E.  L.  A.  Overhead  Line  Construction  Committee,  1911. 
Publications  of  various  manufacturers. 


[2841 


SECTION  5 

INSULATORS 


SECTION  5 

INSULATORS 


TABLE  OF  CONTENTS 

ARTICLE 

General 1 

Porcelain 2 

Wet  Process 3 

Dry  Process 4 

Glazing  and  Firing 5 

Relative  Advantage  of  the  Wet  and  Dry  Processes 6 

The  Properties  of  Insulator  Glazing 7 

Glass  Insulators 8 

The  Cementing  Together  of  Built  up  Insulators 9 

Composition  Insulators 10 

The  Effect  of  Mechanical  Stress  on  Insulators 11 

The  Effect  of  Different  Types  of  Pins  on  Insulator 

Characteristics 12 

Electrical  Characteristics 13 

Ageing  of  Insulators 14 

Testing  Insulators 15 

Insulator  Tests 16 

Elimination  Tests  on  Pin  Type  Insulators 17 

Elimination  Tests  on  Suspension  Type  Insulators 18 

Dry  Arc-over  Test  on  Pin  Type  Insulators 19 

Dry  Arc-over  Tests  on  Suspension  Type  Insulators 20 

Rain  Arc-over  Tests  on  Pin  Type  Insulators 21 

Rain  Arc-over  Tests  on  Suspension  Type  Insulators 22 

Mechanical  Test  on  Pin  Type  Insulators 23 

Mechanical  Tests  on  Suspension  Type  Insulators 24 

Puncture  Tests 25 

Method  of  Measuring  Test  Voltage 26 

Insulator  Protection 27 

Voltage  Distribution  on  the  Suspension  Insulator  String 28 

Effect  of  Leakage 29 

Capacity  of  Insulator  String 30 

Effect  of  Capacity. 31 

Calculated  Characteristics 32 

Grading  the  Capacity  of  Insulators 33 

[287] 


1.  General.     Insulators  may  be  divided  into  three  general  classes: 

(A)  Pin  type. 

(B)  Suspension  type. 

(C)  Strain  type. 

The  first  two  types  are  made  of  porcelain,  glass  or  composition 
and  the  third  of  porcelain,  glass,  composition  and  wood. 

Pin  type  insulators  are  of  a  pedestal  form  and  designed  to  carry 
the  wire  above  the  cross  arms  or  structure  support. 

Suspension  and  Strain  insulators  are  similar  in  type;  so  designed 
that  the  maximum  mechanical  stress  is  applied  along  the  axis  of 
the  insulator  and  not  at  right  angle  thereto,  as  in  the  pin  type  in- 
sulator. 


FIG.  112. — Porcelain  pin 
FIG.  111. — Porcelain  pin  type  msu-  type  insulator,  line  vol- 

lator,  line  voltage  70,000  volts.  tage  45,000  volts. 

2,  PORCELAIN  insulators  are  made  from  clays.  The  clays  are 
formed  from  decomposed  feldspar  and  granites,  and  may  be  divided 
into  two  main  classes: 

(a)  Residual,  or  clay  found  in  the  localities  in  which  it  was 
formed. 

(b)  Sedimentary,  or  clay  that  has  been  transported  by  water 
and  deposited  in  beds. 

Clays  vary  in  their  chemical,  mechanical,  electrical  and  workable 
characteristics,  depending  upon  the  localities  from  which  they  are 
secured.  Insulator  manufacturers  combine  the  various  clays,  each 
making  a  special  mixture  in  order  to  conform  to  their  particular 
method  of  manufacture  and  to  some  .extent  varying  the  mixture, 
depending  upon  whether  the  clay  is  to  be  used  in  the  wet  or  dry 
process  of  manufacture. 

The  mixing  of  the  clay  is  a  mechanical  process  in  which  great 
care  is  taken  to  thoroughly  mix  the  compound  in  order  to  be  assured 
of  a  uniform  product.  The  mixture  is  put  through  a  number  of 
processes  until  a  plastic  thoroughly  mixed  compound  is  produced. 

The  actual  manufacture  of  porcelain  insulators  can  be  divided 
into  two  classes: 

(a)  The  wet  process.     (Art.  3.) 

(b)  The  dry  process.     (Art.  4.) 
10  [  289  ] 


Sec.  5 


INSULATORS 


[  290  ] 


INSULATORS 


Sec.  5 


3.  Wet  Process.  In  the  manufacture  of  insulators  by  the  wet 
process  the  plastic  clay  is  worked  into  a  mould,  care  being  taken 
to  completely  fill  all  the  cavities  in  the  mould.  The  inside  of  the 
piece  is  formed  by  a  plunger.  Some  manufacturers  revolve  the 
mould  and  others  the  plunger. 

All  the  higher  voltage  insulator  parts  are  made  in  this  manner 
except  that  in  the  manufacture  of  very  small  insulators,  the  plunger 
is  so  designed  that  it  also  forms  the  inside  thread  of  the  insulator. 

The  moulds  containing  the  partially  formed  insulators  are  then 
placed  in  a  drying  room  where,  when  partially  dried,  the  mould  is 
removed  and  then  the  piece  is  allowed  to  become  bone  dry.  This 
bone  dry  piece  is  placed  on  a  revolving  mandrel  and  its  surface  is 
scraped  and  finished.  The  parts  that  come  in  contact  with  the 


FIG.  115. — Porcelain  pin  type  insulator,  line  voltage  44,000  volts. 

cement  and  also  the  side  wire  groove  are  turned,  after  which  the 
insulator  is  ready  for  glazing  and  firing. 

4.  Dry  Process.     In  the  manufacture  of  insulators  by  the  dry 
process  the  mixture  of  clay  is  different  from  that  used  in  the  wet 
process.     After  thoroughly  mixing,  it  is  allowed  to  become  dry.     It 
is  then  crushed  into  a  fine  powder  and  pressed  into  shape  in  a  steel 
mould.     The  mass  is  removed  and  when  it  has  become  bone  dry,  it  is 
ready  for  glazing  and  firing. 

5.  Glazing  and  Firing.     Insulators  are  glazed  by  dipping  the 
formed  clay  into  a  glazing  solution,  protecting  the  surfaces  which 
are  to  be  left  unglazed,  from  the  solution.     Different  glazing  mate- 
rials are  necessary  for  different  colored  glazing.     Three  colors  are 
generally  used,  white,  brown  and  blue  or  slate  color.     White  glaze 

[291] 


Sec.  5 


INSULATORS 


is  made  of  the  same  material  as  the  body  of  the  piece  with  an  extra 
fine  quality  of  flux,  i.e.,  feldspar.  Brown  glaze  is  a  pure  earthy 
matter  in  suspension,  manganese  oxide  and  iron  oxide  being  some- 
times used.  Blue  or  slate  colored  glazes  may  be  secured  by  use  of  co- 
balt oxide.  The  pieces  which  have  been  dipped  in  the  proper  glazing 


FIG.  116. — Porcelain  pin  type  insula-      FIG.  117. — Porcelain  pin  type  insula- 
tor, line  voltage  25,000  volts.  tor,  line  voltage  22,000  volts. 

solution  are  then  packed  and  fired  in  kilns,  in  which  the  insulators  are 
so  arranged  that  they  are  protected  from  direct  contact  with  the  fire. 
Proper  firing  requires  from  40  to  48  hours  and  necessitates  con- 
stant attention,  in  order  that  the  insulators  or  parts  shall  not  be 
over  or  under  fired.  After  proper  firing  of  the  insulators  or  insulator 


FIG.  118. — Glass  pin  type  insulator, 
line  voltage  25,000  volts. 


FIG.  119. — Glass  pin  type  insula- 
tor, line  voltage  20,000  volts. 


parts,  they  are  allowed  to  cool  slowly  and  are  then  sorted  to  eliminate 
pieces  having  visible  flaws. 

6.  Relative  Advantage  of  the  Wet  and  Dry  Processes.  Where 
high  voltage  test  requirements  must  be  met,  insulators  made  by 
the  wet  process  should  be  used,  as  the  body  is  dense,  homogeneous 

[  292  ] 


INSULATORS 


Sec.  5 


and  uniform.  Porcelain  insulators  made  by  the  dry  process  do 
not  possess  these  features  to  as  great  an  extent  and  are,  therefore, 
less  dependable  and  should  only  be  used  on  comparatively  low  volt- 
age installations. 


FIG.  120. — Glass  pin  type  insulator,  line  voltage  10,000  volts. 

7.  The  Properties  of  Insulator  Glazing.  Insofar  as  most  com- 
mercial forms  of  insulators  are  concerned,  the  glaze  adds  practi- 
cally nothing  to  the  dielectric  strength,  its  prime  use  being  to  keep 
the  insulator  clean  and  to  present  a  smooth  glossy  surface,  which 
tends  to  prevent  the  permanent  adherence  of  dust. 

All  glazes  which  have  colors  contain  metallic  oxides,  and  even 
some  of  the  transparent  glazes  have  a  large  percentage  of  metallic 
oxide  in  the  form  of  lead,  zinc,  tin,  manganese,  iron  or  cobalt.  All 
of  these  can  be  used  with  success  in  insulator  glazes,  and  are  used 


FIG.  121. — Composition  pin  type  insulator,  line  voltage  38,000  volts. 


by  all  of  the  manufacturers  to  a  large  extent.     The  brown  glazes 
owe  their  coloring  to  iron  and  manganese  oxide. 

The  puncture  value  is  practically  independent  of  the  material 
used  in  glazing.  The  glaze  is  essentially  glass  and,  therefore,  has 
the  same  mechanical  characteristics  as 


8.  GLASS  INSULATORS.  Glass  for  insulators  is  manufac- 
tured from  sand,  lime  and  soda  ash,  which  materials  when  properly 
mixed  are  melted  in  a  furnace  at  a  temperature  of  about  2600°  F. 
The  materials,  as  they  become  completely  melted  are  in  the  form 
of  a  clear  liquid  glass,  which  has  a  plastic  nature.  The  mass  is 
pressed  into  a  mould  of  proper  form  where  it  is  allowed  to  cool, 
after  which  it  is  removed  to  an  annealing  oven  and  thoroughly  an- 
nealed. When  the  insulators  are  removed  from  the  annealing  oven, 

[293] 


Sec.  5 


INSULATORS 


they  are  allowed  to  stand  in  the  open  air  for  about  one  month. 
Then  they  are  sorted  and  tested. 

9.  THE     CEMENTING     TOGETHER     OF    BUILT    UP    IN- 
SULATORS.    Porcelain  and   glass  insulators  particularly  of  the 


FIG.  122. — Porcelain  suspension  type      FIG.  123. — Porcelain  suspension  in- 
insulators.  sulator  string  for  100,000  volts. 


FlQ.  124. — Porcelain  suspension  type 
insulator. 


FIG.  125. — Porcelain  through  pin 

type  insulator,  line  voltage 

23,000  volts. 


[  294  ] 


INSULATORS 


Sec.  5 


higher  voltage  type  are  made  up  of  a  number  of  pieces,  the  proper 
cementing  together  of  which  necessarily  is  of  great  importance. 
Portland  Cement  is  chiefly  used.  Other  cements  are  available, 
the  principal  ones  of  which  are  Sulphur,  Condensite  and  Plaster  of 
Paris.  When  using  cement,  pure  Portland  Cement  of  the  best 


FIG.  126. — Composition  suspension      FIG.  127. — Porcelain  suspen- 
type  insulator.  sion  type  insulators. 

quality  without  any  other  ingredients  is  desirable  in  order  to  be 
assured  of  good  mechanical  strength.  Compared  to  porcelain, 
cement  is  a  good  electrical  conductor  and  therefore  acts  to  a 
greater  or  less  extent  as  a  conducting  condenser  plate  between  the 
two  insulator  parts  which  it  connects. 


FIG.  128. — Porcelain  strain  insulators. 

Condensite  seems  to  be  the  most  successful  cement  that  can  be 
used  for  cementing  together  parts  of  glass  insulators  and  while  it 
has  good  electrical  characteristics,  it  is  very  expensive. 

Sulphur  is  good  mechanically  and  electrically,  but  it  has  a  low 
melting  point  and,  if  the  insulator  heats  slightly,  the  sulphur  will 
melt,  causing  mechanical  failures. 

[295] 


Sec.  5 


INSULATORS 


Plaster  of  Paris  is  comparatively  mechanically  weak  and  there- 
fore seldom  used. 

Care  should  be  taken  to  use  a  cement  which  does  not  act  chemic- 
ally on  the  metal  parts, — for  instance,  producing  an  oxide  on  their 
surface  thus  enlarging  them  and  producing  stresses  which  may  cause 
the  porcelain  to  crack. 

10.  COMPOSITION    INSULATORS    are    made    from    various 
non-conducting  mineral  compounds  and  are  usually  forced  into  the 
moulds  when  in  a  heated  plastic  form.     They  are  generally  built 
in  one  piece.     The  manufacturers  of  such  insulators   claim  very 
high  mechanical  and  electrical  values  for  their  product. 

11.  THE   EFFECT    OF    MECHANICAL    STRESS    ON    INSU- 
LATORS.    In  an  insulator,   as  in   a  steel  spring,   the  maximum 
stresses  to  which  it  is  subjected  will  materially  affect  its  life  and  its 
reliability.     Carrying  the  comparison  still  further,  surges  with  steep 


—  D-Oiomofhoie 


FIG.  129. — Porcelain  strain  insulators. 

wave  front  may  start  an  initial  breakdown  in  the  dielectric,  the 
performance  being  similar  to  that  of  a  spring  worked  to  a  point 
where  the  elastic  limit  is  exceeded,  beyond  which  point  crystalliza- 
tion takes  place  very  rapidly.  If  the  severe  conditions  are  main- 
tained the  fife  of  the  insulator  or  spring  is  necessarily  very  short. 

Since  the  mechanical  requirements  of  insulators  are  usually  de- 
finite and  as  the  mechanical  loading  affects  the  electrical  factors 
of  safety,  such  factors  must  be  considered  in  insulator  design.  The 
suspension  insulator  being  free  from  bending  moments  has  many 
mechanical  advantages  over  the  pin  or  pedestal  type  insulator. 

When  the  insulator  is  light  and  the  span  short  the  internal  me- 
chanical stresses  of  the  insulator  may  usually  be  neglected  with 
safety.  Long  spans  and  large  conductors  produce  high  working 
loads  setting  up  stresses  which,  when  combined  with  the  internal 
stresses,  may  so  lower  the  factor  of  safety  that  destruction  of  the 
dielectric  will  follow. 

[  296  ] 


INSULATORS  Sec.  5 

For  the  porcelain  insulator  it  is  necessary  to  consider  the  stresses 
set  up  by  the  working  loads,  those  due  to  differences  in  the  coeffi- 
cients of  expansion  of  the  porcelain  and  the  metal  parts  and  the 
stresses  set  up  by  the  cement  or  by  the  oxidation  of  the  metal.  For 
glass  insulators,  in  addition  to  the  above,  the  very  uncertain  internal 
stresses,  due  to  uneven  shrinkage  in  cooling,  must  also  be  considered. 

The  safe  mechanical  stresses  that  may  be  applied  to  insulators 
are  generally  determined  experimentally,  as  they  vary  with  the 
material  and  the  design. 

12.  THE  EFFECT  OF  DIFFERENT  TYPES  OF  PINS  ON  IN- 
SULATOR   CHARACTERISTICS.     The    pin    has    practically    no 
effect   on  the  mechanical  characteristics   of  an  insulator,    as   the 
insulator  is  usually  much  stronger  than  the  pin.     A  load  applied  to 
the  insulator  sufficient  to  produce  a  bending  moment  on  the  pin 
will  usually  bend  or  break  the  pin  before  any  damage  occurs  to  the 
insulator.     Metal  pins  or  pins  with  metal  through  bolts,  mounted 
on  grounded  arms  or  on  steel  structures,  carry  the  ground  potential 
into  the  pin  hole  and,  therefore,  increase  the  electrical  stress  on  the 
insulator  head.     Metal  pins  on  wood  arms  have  practically  no  effect 
on  insulator  characteristics.     All  wood   construction  relieves  the 
electrical  stress  on  the  insulator,  as  a  part  of  the  dielectric  strain 
is  taken  up  by  the  wood. 

On  transmission  lines  for  the  higher  voltages  there  is  more  or 
less  leakage  of  electricity  over  the  insulator  to  the  pin.  This  dis- 
charge in  some  cases  produces  a  gradual  charring  or  burning  of  the 
surface  of  the  pin,  that  sooner  or  later  destroys  it.  In  others  the 
wood  does  not  appear  to  burn,  but  a  peculiar  destructive  action  not 
fully  understood  sets  in  and  destroys  the  pin.  The  phenomenon 
resembles  a  rapid  dry  rot.  The  pin  threads  crumble  away  and  the 
fibres  disintegrate  until  the  pin  may  be  crumbled  into  dust  by  the 
hand.  According  to  one  theory  the  leakage  over  the  pin  produces 
a  certain  amount  of  nitric  acid  that  gradually  corrodes  and  destroys  it. 

In  order  to  prolong  the  life  of  wood  pins  it  is  customary  to 
boil  them  in  some  insulating  compound,  such  as  oil  or  paraffin. 
When  this  process  is  carefully  conducted  by  boiling  the  pin  in  a 
vacuum  so  that  the  air  that  is  inevitably  contained  in  the  wood  may 
be  exhausted  and  the  cells  filled  with  the  boiling  preservative  com- 
pound the  life  of  the  pin  is  much  prolonged  and  its  insulating  qual- 
ities much  improved. 

When  glass  insulators  are  used,  insulatorpins  should  be  composed 
of  wood,  steel  shanks  with  wood  thimbles,  or  so  arranged  that  a 
cushion  is  provided  between  the  insulator  and  the  pin.  This  is 
necessary  because  of  the  relatively  low  coefficient  of  expansion  of 
glass,  which,  when  all  metal  pins  are  used,  causes  mechanical  fail- 
ure. _  ..  ^  ...... 

13.  ELECTRICAL  CHARACTERISTICS.     Insulators  should  be 
designed  so  that  they  will  flashover  before  puncturing.     On  pin 
type  insulators  the  ratio  between  puncture  and  flashover  is  about 
1.35  to  1.     The  present  tendency  is  to  increase  this  ratio. 

[  297  ] 


Sec.  5 


INSULATORS 


The  ratio  between  puncture  and  flashover  voltage  for  suspension 
type  insulators  is  practically  the  same.  This  applies,  however,  to 
each  unit  in  the  string.  The  number  of  units  required  in  a  string 
may  change  this  ratio  depending  upon  the  insulator  design,  the 
distance  maintained  between  insulator  units,  and  the  distance  be- 
tween the  insulator  string  and  adjacent  metallic  object. 

Various  types  of  Pin,  Suspension  and  Strain  Insulators  are  illus- 
trated in  Figs.  Ill  to  132. 

14.  AGEING  OF  INSULATORS.  Insulators  that  have  sa£is- 
factorily  passed  factory  and  subsequent  tests  by  the  purchaser  have 


FIG.  130. — Wood  strain  insulator. 


Fio.  131. — Composition  strain  insulator. 


FIG.  132. — Composition  strain  insulator. 


in  some  cases  shown  poor  performance  after  having  been  in  service 
for  several  years.  There  is  considerable  difference  in  opinion  as  to 
whether  there  is  any  change  in  the  physical  properties  of  an  insu- 
lator which  can  be  attributed  to  ageing. 

Fatigue  of  materials  is  known  to  exist  in  cases  where  continuous 
mechanical  stress  is  applied.  It  is  therefore  plausible  to  believe, 
until  some  proof  to  the  contrary  is  furnished,  that  dielectric  ageing 
due  to  electrical  shock  does  exist.  Insulator  failures  may  also 

[  298  ] 


INSULATORS  Sec.  5 

be  due  to  the  gradual  breakdown  of  the  dielectric  rather  than  to 
physical  change  due  to  continued  electrical  shock,  or  may  be  the 
result  of  very  high  frequency  disturbances,  which  will  puncture 
rather  than  flashover  the  insulator. 

The  so-called  ageing  is  probably  due  to  the  development  and 
gradual  spreading  of  small  cracks.  These  cracks  may  be  started  by 
internal  strains,  loads  working  too  near  then*  mechanical  break-down 
point,  cement  expanding  and  over-voltage  surges  (cumulative 
effect). 

15.  TESTING  INSULATORS.     It  is  the  practice  of  many  com- 
panies to  subject  all  insulators  to  tests  in  addition  to  the  usual 
factory  tests.     Such  tests  will  necessarily  vary,  depending  upon  the 
line  under  construction  and  the  availability  of  testing  equipment. 
The  following^ests  are  given  as  representing  general  practice.     Any 
one  or  all  of  them  may  be  applied,  depending  upon  the  desires  of 
the  individual  purchaser. 

16.  INSULATOR  TESTS.     The  tests  on  insulators  may  be  di- 
vided into  five  (5)  sections  as  follows: 

TESTING 

(a)  Elimination  Tests.         1-Pin  type  (Art.  17.) 

2-Sus.  type  (Art.  18.) 

(b)  Dry  Arcing  Tests.          1-Pin  type  (Art.  19.) 

2-Sus.  type  (Art.  20.) 

(c)  Rain  Arcing  Tests.         1-Pin  type  (Art.  21.) 

2-Sus.  type  (Art.  22.) 

(d)  Mechanical  Tests.          1-Pin  type  (Art.  23.) 

2-Sus.  type  (Art.  24.) 

(e)  Puncture  Tests.  1-Pin  type  (Art.  25.) 

2-Sus.  type  (Art.  25.) 

17.  Elimination    Tests    on    Pin    Type    Insulators.     Such   tests 
usually  consist  in  testing  all  the  complete  insulators   by  inverting 
them  in  a  pan  of  water,  of  such  a  depth  as  to  cover  the  center  of 
the  side  wire  groove.     The  inside  of  the  insulators  is  then  filled 
with  water  until  the  thread  is  covered.     Voltage  is  applied  between 
the  water  inside  and  outside  of  the  insulator.     The  value  of  this 
voltage  is  generally  regulated  so  that  it  is  just  below  the  arc-over 
value  of  the  insulator  and  it  is  applied  for  about  one  minute.     By 
such  a  test  the  faulty  insulators  are  eliminated.    The  insulator, 
when  tested  in  this  manner,  will  arc-over  at  a  lower  voltage  than 
when  mounted  in  its  proper  position,  as  the  total  amount  of  leakage 
surface  is  reduced  by  an  amount  proportional  to  the  ratio  of  the 
leakage  surface  covered  by  water,  to  the  original  leakage  surface. 

18.  Elimination  Tests    on    Suspension   Type    Insulators.     Each 
unit  is  tested  in  the  same  manner  as  that  used  for  testing  Pin  In- 
sulators, thus  eliminating  any  defective  units  before  assembling. 
Completed  insulator  strings  may  also  be  so  tested. 

[  299  ] 


Sec.  5  INSULATORS 

19.  Dry  Arc-Over  Test  on  Pin  Type  Insulators.*     A  proportional 
number  of  assembled  insulators  are  mounted  on  metal  pins  under  con- 
ditions resembling  those  to  which  the  insulator  will  be  subjected 
when  in  service,  and  voltage  is  applied  between  the  pin  and  a  rod 
attached  to  the  insulator  in  a  position  similar  to  that  which  the 
line  wire  will  occupy.     The  arc-over  voltage  obtained  in  such  a  test 
will  be  considerably  higher  than  that  obtained  in  the  elimination 
tests. 

20.  Dry  Arc-Over  Tests  on  Suspension  Type  Insulators.*    A  pro- 
portional number  of  units  for  given  service  conditions  are  assembled 
and  suspended  from  a  metal  hook  or  clamp.     A  rod  is  then  attached 
to  the  wire  clamp  of  the  lowest  insulator  in  a  position  similar  to 
that  which  the  line  wire  will  occupy.     Voltage  is  applied  between 
the  cap  of  the  top  insulator  and  the  rod  until  a  flashover  occurs. 
The  arc-over  voltage  of  several  units  in  series  will  not  be  a  multiple 
of  that  of  one  unit,  but  each  additional  unit  will  increase  the  flash- 
over  voltage  by  approximately  the  amount  the  second  unit  adds  to 
the  arc-over  voltage  of  one  unit  when  two  are  placed  in  series. 

21.  Rain  Arc-Over  Tests  on  Pin  Type  Insulators.     There  are  so 
many  variables  entering  into  results  obtained  in  this  test  that  it  is 
not  safe  to  compare  various  types  of  insulators  unless  all  the  con- 
ditions of  the  test  are  similar.     Some  of  the  conditions  causing  dis- 
crepancies are  as  follows : 

The  quality  of  water. 

The  quantity  of  water. 

The  pressure  of  water. 

The  distance  of  nozzles  from  unit  under  test. 

The  fineness  of  the  spray. 

The  angle  of  contact  with  the  unit  under  test. 

The  barometric  pressure. 

Some  of  these  conditions  are  difficult  to  regulate.  The  quality 
of  water  will  vary  with  the  locations  at  which  the  test  is  made.  Care- 
ful experimenters  have  found  that  it  is  practically  impossible  to 
exactly  duplicate  results,  even  with  laboratory  methods  and  appa- 
ratus. This  test,  however,  will  give  a  general  idea  of  what  the  in- 
sulators will  do  under  adverse  conditions  and  when  made  at  any 
one  testing  station,  furnishes  fairly  reliable  comparative  information. 
The  usual  method  of  making  this  test  is  to  mount  the  insulators 
in  the  same  manner  as  that  used  when  making  the  dry  arc-over 
test,  throwing  a  fine  spray  of  water  on  the  insulator  from  an  angle 
of  about  45°  to  the  horizontal.  The  precipitation  is  adjusted  to 
equal  approximately  1  inch  in  five  minutes.  A  determination  of 
the  flashover  voltage  is  obtained  during  precipitation  which  value 
obviously  will  be  materially  lower  than  the  dry  flashover  voltage. 

*  The  arc-over  voltage  of  insulators  decreases  with  increasing  altitudes  or 
decreasing  barometric  pressure.  For  instance,  if  the  arc-over  voltage  is  "E"  at 
sea  level,  it  will  be  considerably  less  than  "E"  at  a  higher  altitude,  say  6000  feet. 
Allowance  should,  therefore,  always  be  made  for  thia  phenomenon. 

[  300  ] 


INSULATORS  Sec.  5 

22.  Rain  Arc-Over  Test  on  Suspension  Type  Insulators.    In- 
sulator strings  are  mounted  in  a  manner  similar  to  that  used  in  meas- 
uring the  dry  arc-over  value  and  a  fine  spray  of  water  is  thrown  upon 
the  assembled  string  at  an  angle  of  45°  from  the  horizontal,  the  pre- 
cipitation also  being  regulated  to  equal  approximately  1  inch  in 
five  minutes.     The  wet  arc-over  voltage  is  obtained  during  pre- 
cipitation.    • 

23.  Mechanical  Test  on  Pin  Type  Insulators.    The  usual  test 
applied  to  pin  type  insulators  consists  of  mounting  the  insulator  on 
a  rigid  pin  and  applying  a  pressure  at  the  side  tie  wire  groove  in  a 
direction  perpendicular  to  the  vertical  axis  of  the  insulator.     In 
general,  it  may  be  said  that  a  high  voltage  insulator  should  stand  a 
pull  that  will  bend  or  break  any  metal  pin  on  which  it  is  likely  to  be 
used.     For  general  use,  a  two  thousand  pound  pull  which  is  an  aver- 
age value  to  apply  in  such  tests,  should  not  cause  any  fracture. 

24.  The  Mechanical  Tests  on  Suspension  Type  Insulators  consist 
in  applying  tension  between  the  metal  cap  on  the  top  of  the  unit  and 
the  connection  link  beneath  the  unit.     The  ultimate  breaking  load 
for  suspension  insulators  varies  from  4,000  to  30,000  pounds  in  ac- 
cordance with  the  design  of  the  insulator. 

25.  Puncture  Tests.     Tests  on  a  certain  percentage  of  each  1000 
insulators,  not  exceeding  one-quarter  of  one  percent  should  be  made 
to  determine  the  ability  of  the  insulator  to  resist  puncture.     This 
test  is  best  made  by  submerging  the  insulator  in  oil. 

Suspension  insulators  should  be  completely  assembled  with  the 
standard  fittings  with  which  they  are  to  be  used  in  service. 

With  pin  type  insulators  there  should  be  attached  to  the  head  of 
the  insulator,  wires  representing  the  tie  and  line  wires,  and  a  metal 
pin  should  be  placed  in  a  proper  manner  in  the  pin  hole. 

The  test  should  then  be  applied  to  the  fittings  in  each  case.  The 
puncture  value  obtained  under  these  conditions  should  not  be  less 
than  135  percent  of  the  dry  flashover  voltage. 

In  making  the  test,  apply  to  the  insulator  a  voltage  30  to  40  per- 
cent below  the  dry  flashover  value  for  30  seconds,  then  raise  the 
voltage  by  steps  at  a  rate  of  about  1000  volts  per  second  until  punc- 
ture occurs. 

26'  Method  of  Measuring  Test  Voltage.  The  method  of  deter- 
mining the  value  of  the  test  voltage  should  be  in  accordance  with  that 
described  in  Art.  23a  Sec.  6  Part  I. 

27.  INSULATOR  PROTECTION.  Power  arcs  are  frequently 
started  by  lightning  discharges  and  result  in  burning  and  breaking 
of  the  transmission  cables,  whereupon  the  towers  are  subjected  to 
unbalanced  stresses  which  sometimes  cause  their  failure.  Light- 
ning arresters,  suitable  for  the  protection  of  station  apparatus, 
are  available,  but  such  arresters  do  not  protect  the  lines  themselves. 

A  number  of  special  devices  may  be  employed  at  points  on  the 
line  where  lightning  is  likely  to  be  severe,  in  order  to  prevent  the 

[  301  ] 


Sec.  5 


INSULATORS 


burning  of  conductors  and  the  shattering  of  insulators.  The  arcing 
horns  and  the  double  ring  scheme  are  two  such  devices.  The  former 
consists  of  two  horns,  one  connected  to  the  insulator  head  and  the 
line  and  the  other  to  ground,  the  gap  between  them  being  adjusted 
so  that  a  discharge  will  take  place  across  it,  rather  than  across  the 
insulator.  The  double  ring  device  consists  of  a  ground  ring  sup- 
ported by  the  crossarm  so  that  it  encircles  the  lower  petticoat  of  the 
insulator  with  several  inches  clearance,  and  of  a  second  ring  connected 
to  the  line  and  resting  near  the  edge  of  the  top  petticoat.  A  flash- 
over  will  usually  occur  between  the  rings  without  shattering  the 
insulator. 


2  3 

RESISTANCE 


FIG.  133. 


28.  THE  VOLTAGE  DISTRIBUTION  ON  THE  SUSPENSIpN 
INSULATOR  STRING,  where  all  units  are  alike  varies  depending 
upon  the  ratio  of  the  leakage  current  to  the  capacity  current. 

If  leakage  predominates  the  voltage  will  be  equally  distributed 
between  the  units  of  the  suspension  string,  but  if  the  capacity  effect 
predominates  the  voltage  will  be  highest  across  the  insulator  nearest 
the  line  wire  and  gradually  diminish ;  the  unit  nearest  the  ground 
having  the  least  voltage  stress. 

29.  Effect  of  Leakage. 

E  =  total  voltage  across  string. 

r2  =  leakage  resistance  of  each  unit. 

it  =  current  flowing  over  insulator  surface  from  line  to  ground. 

n  =  number  of  insulator  units  in  a  string. 

[  302  ] 


INSULATORS 


Sec.  5 


If  a  number  of  equal  resistances  are  connected  in  series  in  a  string 
as  in  Fig.  133  and  voltage  E  is  applied  across  the  string  the  total 
current  is 

E 


The  voltages  across  all  resistances  are  equal; 

ei=e2  ........................  =en  =  itr2 

and 

E  =ne!  =nea  =  .........  =nen 

This  represents  the  voltage  distribution  when  both  the  upper  and 
lower  insulator  surfaces  are  wet  and  the  leakage  resistance  rather 
than  the  capacity  of  the  insulator  string  determines  the  voltage 
distribution. 


en 


VOLTS 


The  voltage  distribution  due  to  the  combination  of  the  capacities 
of  the  insulators  in  the  string,  from  line  to  ground  and  from  each 
insulator  to  ground,  is  as  follows: 

Let  Fig.  134  represent  a  string  of  suspension  insulators  grounded 
at  one  end,  G,  as  at  the  tower.  Each  insulator  may  be  represented 
as  a  condenser  with  a  capacity  Ca,  and  each  connecting  link  and  cap 
may  be  represented  as  a  condenser  with  a  capacity  ci  to  ground. 
Greater  capacity  current  passes  through  insulator  (1)  than  through 

[303] 


Sec.  5  INSULATORS 

insulator  (2),  etc.,  hence,  the  voltage  across  the  insulator  (1)  is 
greater  than  across  insulator  (2),  etc.,  or,  the  voltage  is  not  balanced 
along  the  string.  The  greater  Ci  is,  when  compared  to  c2  the  greater 
the  unbalancing.  Also  the  greater  the  number  of  units  in  a  string, 
the  greater  the  unbalancing.  The  voltage  across  the  different 
insulators  of  a  given  string  can  be  readily  calculated  if  the  ratio 

—  Ms  known,  and  it  is  assumed  there  is  no  surface  leakage  or  corona. 

Ci 

Leakage  or  corona  will  not  appreciably  affect  the  results  at  operating 
voltage. 

Referring  to  Fig.  134  an  expression  for  the  total  capacity  of  a 
string  of  n  insulators  may  first  be  written. 

30.  Capacity  of  Insulator  String. 

Let  c2  =  x  d 

Then  the  total  capacity  for  a  string  of  n  insulators  is; 
One  insulator 


Two  insulators 


— h— 

Ci+C2        C2 

Three  insulators 


k2+c2 


For  a  string  of  n  insulators. 

k  n-i 

r-i  —  =       -  — 

C2  +kn- 


,  2  /  1    . 

kn  =  Ci  +c2  --  r-i  —  =  c2  1  -  —  H 

C2  +kn-i  V   X 

31.  Effect  of  Capacity.    Let  E  be  the  voltage  across  the  string 
to  ground  (Fig.  135). 

i     =  total  capacity  current. 

_    c2     c2  =  mutual  capacity  or  the  capacity  of  each  insulator. 

Ci      Ci  =  capacity  to  ground. 
kn  =  total  capacity  of  the  string. 

k    =^- 

Ci 

Then 

i     =  2  TT  f  kn  E 

ii'  =  2  TT  f  ci  E 

Then  the  voltage  across  the  first  or  line  insulator  is 
i-i'!       27rfE  (kn-cQ 

61 


27rfc2 

C2  X 


(kn-Cl)_  E   (k-1) 

Hj    — 


[304] 


INSULATORS 


Sec.  5 


"I 


FIQ.  135. 


JOO 

1* 

80 

I" 

Z  60 
O 
tn  60 

I40 

3  30 

2 

20 
10 

V 

\ 

\ 

\ 

Y 

NO. 

3F  Ul 

ITS 

N  SEF 

IES- 

)(  -: 

\ 

\ 

No.  1  IS  UNIT  NEXT  TO  LINE 
ASSUMING: 

cyc,=2     «,=ioo 

V 

V. 

" 

vs 

Jl-3 

~ 

X 

^ 

^ 

__ 

\ 

^^, 

**^. 

n=? 

,,  • 
Fio.  136.—  C 

H 
^> 
0 

5™ 

> 

o 
2 

91234567 
UNIT  NUMBER 

alculated  voltage  across  different  insulators  in  a  string  of  "n"  units. 

v 

> 

NO. 

DF  Ul 

ITS 

N  SE 

IES- 

n* 

\ 
* 

\ 

No.  1  IS  UNIT  NEXT  TO  LINE 
ASSUMING: 

\^ 

n-3 

- 

^ 

^ 

\. 

»=4 

X 

^ 

^ 

S 

^ 

it-b 

—  . 

•  — 

— 

_H 

7 

01234  567 

UNIT  NUMBER 

FIQ.  137. — Calculated  voltage  across  different  insulators  in  a  string  of  "n"  units. 

[  305  ] 


Sec.  5  INSULATORS 

The  voltage  e2  across  the  second  insulator  is  found  thus: 


x 

27T  f  d 


i'2  =  2  TT  f  e'2 
Therefore 

fl)=E 
x 


k( 


2  7T  f  C2  X2 

For  the  third  insulator 
x  (x  +  1)  (k  — 


e3   =  E 


For  the  nth  insulator 


(k-l)-x  (x  +  1) 


From  the  above  the  following  equations  may  be  written  for  solv 
ing  numerical  problems. 

Total  capacity  of  a  string  of  n  insulators. 


2c2+ci  — c22 


Write  fraction  to  n  — 1  of  the  2  c2+Ci  terms. 


2c2+Cl 


100 
90 

do 

H 

Z70 

3 

Z60 
0 

J250 
040 

§30 
x 
20 

1 

^_ 

NO.  lOF  UKITS 

H  SERIE6,j«=SJ 

^ 

^ 

S^ 

No 
AS' 

1  1< 

UM 

u^ 

NG 
^lc\ 

IIT  t 

JEX 

rroLlf 

IE 

\ 

§ 

^ 

n-3 

=  10 

e 

,=10 

1 

\ 

^N 

*s~-^ 

^^__ 

n-4 

N, 

?s 
X 

4si 

\ 

'  

n=5 

*s 

^^_ 

•*•  *^ 

—'    <•• 

n=/ 

01234567 

UNIT  NUMBER 

Fio.  138. — Calculated  voltage  across  different  insulators  in  a  string  of  "n"  units. 

[  306  ] 


INSULATORS 


Sec.  5 


100 
90 
h80 
l*> 

0  GO 
</> 
^350 
o 

s40 

5  30 
20 
10 

"S 

^ 

NO. 

OF  U 

NITS 

N   SE 

HIES, 

n= 

!, 

^ 

^ 

71  = 

S 

*•> 

S 

\ 

1  _. 

n= 

NO.1  IS  UNIT  NEXT  TO  LINE 
ASSUMING 
C2//6.=20     «!=100 

X 

\> 

5 

-  — 

—   _ 

n~i 

\ 

•^-^ 

•  — 

>^ 

•—  

n^ 

^ 

±- 

"^•fc—  - 

_„_ 

•  

—  •  — 

n 

=10 

1             2             3            A              5             6             7 

8             9            10 

UNIT  NUMBER 
FIG.  139. — Calculated  voltage  across  different  insulators  in  a  string  of  "n"  units. 


!« 


10 


01234567S910 

UNIT  NUMBER 

FIG.  140. — Calculated  voltage  across  different  insulators  in.  a  string  of  "n"  units. 


(2)     Volts  across  first  or  line  insulator  of  string  of  n  is 


Ci 

(3)     The  voltage  across  the  mth  insulator  of  a  string  is 
e  m-i  +e  m-2  +  .......  +ei—  E 


em=  em— 1 


(4) 


307  1 


Sec.  5  INSULATORS 

When  the  arc-over  voltage  of  a  single  unit  alone  ea  is  taken  for  ei. 
(4a)     Ea=  ,  a      =  arc-over  voltage  of  string. 

K.  —  J.  ._ 

(5)     String  efficiency  =       a    =     .,  _ 

String  efficiency  is  materially  effected  by  the  type  of,  and  the 
spacing  between  insulator  units,  as  the  performance  of  some  types 
of  closely  spaced  insulators  results  in  the  breaking  down  of  the  air 
paths  between  the  terminals,  before  a  flashing  potential  is  obtained 
across  any  unit. 

32.  Calculated  Characteristics.  The  method  of  calculating 
the  characteristics  of  insulators  in  series,  for  different  lengths  of 

string  and  different  values  of  — ,  using  formulae  1,  2,  3,  4  and  5  fol- 
lows: 


TABLE  55 

Ratio  cj/ci 

1 

2 

5 

10 

15         20 

50 

100 

500 

1000 

No.  of  insula- 
tors in  series 

Values  of  K 

1 

2~000 

sTooo 

000 

11.000 

16.000 

21.000 

51.000 

101.00 

501.00 

1001.00 

2 

1.667 

2.200 

3.728 

6.238 

8.742 

11.244 

26.247 

51.21 

251.25 

501.25 

3 

1.625 

2.048 

3.135 

4.842 

6.387 

8.197 

18.998 

34.89 

173.22 

334.89 

4 

1.619 

2.012 

2.927 

4.263 

5.546 

6.814 

14.350 

26.87 

126.87 

251.87 

5 

1.618 

2.003 

2.846 

3.988 

5.049 

6.083 

12.172 

22.20 

102.20 

202.20 

6 

« 

2.001 

2.814 

3.851 

4.777 

5.676 

10.777 

19.19 

85.83 

169.29 

7 

«« 

2.000 

2.801 

3.781 

4.623 

5.421 

9.863 

17.15 

74.36 

145.82 

8 

«« 

2.795 

3.743 

4.574 

5.265 

9.238 

15.69 

65.68 

128.18 

9 

«« 

2.793 

3.724 

4.505 

5.178 

8.797 

14.63 

59.03 

114.63 

10 

" 

2.792 

3.713 

4.465 

5.108 

8.481 

13.85 

53.85 

103.85 

11 

<« 

« 

3.708 

4.447 

5.069 

8.251 

13.23 

49.68 

95.09 

12 

" 

" 

3.705 

4.415 

5.044 

8.083 

12.84 

46.22 

91.85 

13 

" 

" 

3.703 

4.411 

5.036 

7.958 

12.52 

43.29 

81.75 

14 

" 

" 

3.702 

4.409 

5.024 

7.865 

12.33 

40.93 

76.58 

15 

' 

;' 

3.702 

4.407 

5.015 

7.796 

12.17 

38.81 

72.21 

To  find  the  total  capacity  of  the  string,  kn,  take  the  k  above  for  the  required 
ratio  — '  anc^  ^ne  8iven  number  of  insulators  in  series  and  multiply  by  ci. 

As  an  example  of  use  of  formulae,  assume 

c*       5 

-  =x 


Cl 


kn 


n  =  3     E  =  100     k=-^- 
From  (1)     kn  =  Ci-f-c2  — 


2  c2-f-ci  —  c22 


2c2+ci 


[  308  ] 


INSULATORS  Sec.  5 


10+1 
From  (2)     Gl=  —  (k-1) 

100 

=^R3.135-1) 
o 

e  '       ~E 


From  (3) 


=  427+ 42.7-100  =313 
o 

e=e  i  e  3~1  +  e  3~2  ~E=      I  e2+et-E 

x  x 

0  ,31.3+42.7-100 

63  =  31. 3  H — - —      — =26 

o 

E=  el  +e2+e3=  100 

If  42.7  is  considered  as  the  arc-over  voltage  of  a  unit  then  the 
string  efficiency  is — 

OT=°-78=78v / 1,:,,*,  v    1     | 

Figs.  136  to  140  and  Table  55  are  given  as  an  aid  in  calculating  the 
voltage  distribution  across  an  insulator  string.  The  values  in  each 
figure  are  calculated  for  various  numbers  of  insulators  in  a  string, 

assuming  ratios  of  —  -  and   the  voltage   across  the  insulator  next 

to  the  line  equal  to  100  kv. 

If  this  voltage  is  less,  the  voltage  across  the  remaining  insulators 
of  the  string  will  also  be  proportionately  less. 

Values  of  k  are  given  in  Table  55  for  various  values  of  —  —  and 

for  various  numbers  of  insulators  in  series. 

To  demonstrate  the  use  of  the  table  and  curves  the  following 
problem  is  given: 

Problem.  Find  the  distribution  of  voltage  across  each  unit  of 
a  suspension  insulator  string  consisting  of  four  units  where  the 
voltage  from  the  line  conductor  to  ground  is  100  kv.,  assuming  a 
ratio  of  mutual  capacity  to  capacity  to  ground  of  five. 

x=-^-=5        n=4        E=100kv. 

From  Table  55  for  —  =  5  and  n  =  4. 

Findk=  2.927. 

[309] 


Sec.  5 


INSULATORS 


Then 


100 


-  nr  (2.927-1)  =  38.54  kv. 


String  efficiency 


100 


4  x  38.54 


0.649=  64.9%. 


From  curve  Fig.  137  assuming  ei  =  100  kv. 

The  relative  values  of  e2,  e3  and  e4  may  be  found,  and  the  actual 

value  then  obtained  by  proportion. 

From  Fig.  137    Actual 

d  100.00  kv.=    38.54 

e2  68.5    "     =    26.35 

e3  51.0    "     =     19.60 

e4  42.5    "     =     16.35 


100.84  error  .84% 

Assuming  that  50  kv.  is  the  flashover  value  of  one  unit,  the  flash- 
over  value  of  the  string  is 

Ea  =  50  x  4  x  0.649  =  129.8  kv. 
The  drawn  curves  in  Fig.  141  are  the  theoretical  ones  for  ea  =  74 

kv.  for  dry  insulators  and  —  =  10,  —^-  =  15,  and  —^-  =  20. 


400 

c2/rJ 

20 

^ 

^ 

r 

CO 
OOQQ 

^ 

2 

kl 

^ 

''' 

s 

100 

^ 

> 

X-MBASUR 
CURVES  C/> 

ED  ARC  OVER- 
T  NO.  5 
LCULATED  FOR 

* 

f  '     ° 

I 

1 

012345678 

NUMBER  OF  INSULATORS 

PER  STRING 

FIG.  141. — Comparison  of  calculated  and  test  curves. 

The  crosses  (Fig.  141)  are  the  measured  values.     This  illustrates 
the  effect  of  automatic  grading  due  to  corona  and  leakage.     For 

short  strings  the  points  follow  the  curve  for  —  =  10,  which  if  con- 
tinued would  give  a  very  low  flashover  efficiency. 

Automatic  grading  causes  the  points  to  gradually  shift  to  the 

curve  for  — ^-  =  20.     The  actual  value  of  — Bunder  operating  voltage 

[310] 


INSULATORS 


Sec.  5 


is  probably  between  5  and  10.  Thus,  while  arc-over  tests  for  long 
strings  may  indicate  a  fair  efficiency,  the  insulator  string  is  in  reality 
operating  at  a  very  bad  unbalance  of  voltage. 

The  curves  in  Fig.  142  illustrate  how  moisture  affects  the  voltage 
distribution  of  the  string.  The  curve  of  dry  arc-over  voltage  follows 
the  law  of  capacities.  The  curves  of  rain  arc-over  voltages  follow 
the  law  of  resistances. 


IUU 

\ 

V 

3, 

s 

TEST  NO.5 
22°C  -  74Cm.b 

z 
u 

o 

t    80 

Ul 
0 

|    TO 

CO 

60 

500 

400 

tn 
1- 

_j 

Ss 

c 

s 

^ 

\ 

x 

^ 

' 

<& 

$' 

> 

,' 

1 

¥' 

,& 

? 

^^ 

^ 

*" 

s 

& 

r 

KTLOVC 

.$• 

X 

r^ 

/ 

/ 
/' 

^ 

fe 

f<y 

f/\  . 

/ 

p 

(<C 

? 

/ 

/ 

^ 

- 

23456789 

NUMBER  OF  INSULATORS  PER  STRiNG 

FIG.  142. — Test  characteristic  curves  of  suspension  insulators. 


33.  GRADING  THE   CAPACITY  OF  INSULATORS.     It  has 

been  suggested  and  rather  strongly  urged  abroad  that  insulator 
capacities  be  graded,  i.e.  an  insulator  having  a  large  capacity  placed 
next  to  the  line,  one  having  a  small  capacity,  placed  next  to  the  sup- 
port and  the  capacity  of  the  intermediate  insulators  graded  between 
the  capacity  01  the  two  extreme  insulators. 

[311] 


Sec.  5  INSULATORS 

Since  the  current  varies  on  each  section,  the  capacity  must  vary 
accordingly,  in  order  that  a  uniform  distribution  of  stress  may  result. 
To  obtain  uniform  stress  distribution  in  this  manner  would  require 
each  unit  in  the  series  to  be  different  in  type  from  every  other  unit, 
and  the  advantage  of  the  interchangeability  of  parts  would  be  lost. 
Although  considered  impracticable  for  the  suspension  insulator 
units,  such  methods  of  distributed  capacity  have  been  found  very 
valuable  in  distributing  the  stress  in  the  pin  type  insulator. 


FIG.  143. — Illustrating  the  effect  of  insulator  capacity  on  voltage  distribution. 

That  the  stress  distribution  can  be  controlled  by  a  change  in  the 
capacity  of  each  insulator  and  from  each  insulator  to  ground  is 
illustrated  by  the  following: 

Fig.  143  illustrates  a  suspension  insulator  composed  of  two  sections 
the  upper  having  a  small  electrostatic  capacity  in  comparison  to 
that  of  the  lower  insulator.  The  flash-over  value  of  the  small  in- 
sulator is  57  kv.  but  when  a  potential  of  62  kv.  was  applied  to  the 

1312] 


INSULATORS 


Sec.  5 


series  the  small  insulator  was  stressed  to  its  flash-over  potential. 
The  photograph  was  taken  with  62  kv.  on  the  series  and  shows  the 
charging  current  of  the  large  insulator  forming  an  arc  over  the 
smaller.  To  flash  over  the  entire  series,  requires  150  kv. 

Fig.  144  illustrates  an  insulator  of  relatively  small  electrostatic 
capacity  between  two  sections  of  larger  capacity.  When  tested 
alone,  flashing  potential  of  the  small  unit  was  57  kv.  The  photo- 


FIG.    144. — Illustrating   the  effect  of  insulator  capacity  on  voltage  distribution. 


graph  was  taken  with  97  kv.  applied  to  the  series,  which  was  suf- 
ficient to  overstress  the  small  insulator,  while  300  kv.  were  required 
to  flashover  the  series.  When  it  is  considered  that  the  over-stressed 
member  shown  in  Fig.  144  adds  but  little  to  the  flashover  of  the 
remaining  insulators,  it  is  seen  why  insulator  designs  may  be  very 
inefficient. 

[313] 


Sec.  5  INSULATORS 


BIBLIOGRAPHY 

N.  E.  L.  A.,  June,  1913,  A.  O.  Austin. 

A.  I.  E.  E.,  June,  1911,  A.  O.  Austin. 

A.  I.  E.  E.,  June,  1913,  Peek,  Thomas  &  Sanford. 

A.  I.E.  E.,  May,  1912,  F.  W.  Peek,  Jr. 

Publications  of  Various  Manufacturers. 


[314] 


SECTION  6 


PART  I 
TRANSFORMERS  AND  INDUCTION  REGULATORS 


PART  II 


LIGHTNING   PHENOMENA    IN    CONNECTION 

WITH  ELECTRIC  CIRCUITS,  PROTECTIVE 

APPARATUS,  GROUNDING 


SECTION  6 

PART  I-TRANSFORMERS  AND  INDUCTION 
REGULATORS 


TABLE  OF  CONTENTS 

ARTICLE 

Definitions 1 

Transformer  Construction. 

General 2 

Cores 3 

Coils 4 

Cases 5 

Transformer  Equations. 

General 6 

Hysteretic  Losses 7 

Eddy  Current  Losses 8 

Copper  Losses 9 

Exciting  Current 10 

Induced  Voltage 11 

Ratio 12 

Equivalent  Resistance  and  Reactance 13 

Features  of  Design 14 

Insulation 15 

Temperature 16 

Efficiency 17 

Regulation 18 

Magnetic  Fatigue  or  the  Ageing  of  Steel 19 

Power-factor 20 

Transformer  Characteristics 21 

Transformer  Testing 22 

Insulation 23 

Heating  Tests 24 

Core  Loss  and  Exciting  Current 25 

Resistance  Measurements 26 

Copper  Loss 27 

Reactance  Drop 28 

Regulation 29 

[317] 


Sec.  6  TRANSFORMERS 

ARTICLE 

Ratio 30 

Polarity 31 

Transformer  Specifications 

Transformers 32 

Transformer  Oil 33 

The  Operation  of  Large  vs.  Small  Transformer 34 

Polyphase  Transformers \TWSv 35 

Parallel  Connecting  of  Transformers 36 

Scott  Transformation  Vector  Analysis 37 

Special  Series  Incandescent  Lighting  Transformers 38 

Induction  Regulators 

General  description 39 

Pole  Type  Regulators 40 

Induction  Regulator  Tests 41 


[318] 


1.  DEFINITIONS.     Transformers  and  alternating  current  voltage 
regulators  are  Stationary  Induction  Apparatus  which  are  defined 
as  apparatus  changing  electrical  energy  to  electrical  energy  through 
the  medium  of  magnetic  energy.     It  comprises  several  forms  dis- 
tinguished as  follows: 

(a)  TRANSFORMERS,   in  which  the  primary  and  secondary 
windings  are  insulated  one  from  another. 

A  primary  winding  is  that  winding  of  a  transformer,  or  of  n 
induction  motor,  which  receives  energy  from  an  external  source. 

A  secondary  winding  is  that  winding  of  a  transformer,  or  of  an 
induction  motor,  which  receives  energy  from  the  primary  by  in- 
duction. 

NOTE:  The  terms  "High- voltage  winding"  and  "Low-voltage 
winding"  are  suitable  for  distinguishing  between  the  windings  of 
a  transformer,  where  the  relations  of  the  apparatus  to  the  source 
of  power  are  not  involved. 

(b)  AUTO-TRANSFORMERS,  also  called  COMPENSATORS, 
in  which  a  part  of  the  primary  winding  is  used  as  a  secondary  wind- 
ing, or  vice  versa. 

(c)  POTENTIAL  REGULATORS,  in  which  one  coil  is  in  shunt 
and  one  in  series  with  the  circuit,  so  arranged  that  the  ratio  of  the 
transformation  between  them  is  variable  at  will.     They  are  of  the 
following  three  classes: 

(1)  Contact  Voltage  Regulators,  also   called  Compensator  Reg- 
ulators, in  which  a  varying  number  of  turns  in  one  or  both  of  the 
coils  is  adjustable. 

(2)  Induction  Potential  Regulators  in  which  the  relative  positions 
of  the  primary  and  secondary  coils  are  adjustable. 

(3)  Magneto  Potential  Regulators  in  which  the  direction  of  the 
magnetic  flux  with  respect  to  the  coils  is  adjustable. 

(d)  REACTORS  or  REACTANCE  COILS,  also  called  CHOKE 
COILS;    a  form  of  stationary  induction  apparatus  used  to  supply 
reactance  or  to  produce  phase  displacement. 

(e)  CONSTANT    CURRENT    TRANSFORMERS    or    those    in 
which  the  primary  voltage  is  maintained  constant  and  the  secondary 
voltage  varies  with  the  load,   the  secondary    current    remaining 
approximately   constant.     These    characteristics   are   obtained   by 
automatically    increasing    or    decreasing    the    separation    between 
the  primary  and  the  secondary  coils,  thus  decreasing  or  increasing 
the  voltage  generated  in  the  secondary,  due  to  the  increased  or  de- 
creased  magnetic   leakage   between   the   coils.     The   voltage   thus 
varies  with  the  impedance  of  the  load,  while  the  current  remains 
constant  within  the  range  of  the  regulating  characteristics  of  the 
transformer. 

TRANSFORMER  CONSTRUCTION 

2.  General.     Transformers  consist   of   a  laminated    steel    core 
upon  which  are  wound  insulated  coils  of  copper  wire.     This  assembly 

[319] 


Sec.  6 


TRANSFORMERS 


of  copper  and  steel  is  placed  in  a  metallic  tank  containing  oil,  which 
reinforces  the  insulation  of  the  coils  by  the  insulating  strength  of 
the  oil.  The  tank  also  protects  the  transformer  windings  from 
injury.  The  connections  from  the  coils  are  brought  out  through 
insulated  bushings  varying  in  type  with  the  voltage  requirements. 
(Figs.  145  to  148.) 

3.  Cores.  Transformer  cores  consist  of  a  number  of  sheets  of 
steel  (called  laminations)  insulated  from  one  another  by  a  thin  film 
of  oxide,  varnish  or  similar  substance.  These  sheets  vary  in  thick- 
ness from  0.014  inches  to  0.025  inches,  depending  upon  the  capacity 
and  frequency  of  the  transformer  under  construction.  They  are 


FIG.  145. — Condenser  type 

transformer  bushing, 

60,000  volts. 


FIG.  146.— Oil  insulated 

transformer  bushing, 

70,000  volts. 


so  constructed  in  order  to  minimize  core  loss  due  to  eddy  currents. 
(Art.  8). 

Transformers  are  of  two  fundamental  designs,  namely: — the  shell 
and  the  core  type. 

In  the  shell  type  the  iron  circuit  surrounds  the  transformer  coils. 

In  the  core  type  the  copper  windings  surround  the  iron  core. 

All  other  forms  of  transformers  may  be  considered  as  modifi- 
cations of  these  two  simple  forms.  A  clear  idea  of  the  relation 
existing  between  these  fundamental  types  may  be  secured  from 
Fig.  149.  It  is  evident  from  this  figure  that  an  interchange  of  .the 

[320] 


TRANSFORMERS 


Sec.  6 


iron  and  copper  elements  will  transform  the  shell  type  into  the  core 
type  and  vice  versa. 

Distributed  shell  and  core  types  of  construction  are  developed 
from  the  simple  forms  as  shown  in  Fig.  149.  These  types  are  devel- 
oped from  the  simple  forms  by  the  addition  of  two  small  iron  cir- 
cuits to  the  shell  type  or  two  small  copper  elements  to  the  core  type. 
The  distributed  shell  type  is  sometimes  built  with  the  four  parts 
of  the  magnetic  circuit  interlocking,  and  is  often  called  the  "cru- 
ciform type." 

The  distributed  shell  type  for  small  low  voltage  transformers 
can  be  constructed  more  cheaply  for  a  given  performance  than 
the  simple  shell  or  core  type  on  account  of  its  short  mean  turn  of 


FIG.  147. — Method  of  insulating  leads 

from  case,  6600/110-220  volt 

transformer. 


FIG.  148. — Method  of  insulating  leads 

from  case,  6600/110-220-440 

volt  transformer. 


iron,  and  in  other  respects  has  equally  good  operating  character- 
istics. For  higher  voltages  and  fairly  small  capacities  the  single 
core  type  is  frequently  used. 

Silicon  steel  is  the  material  used  at  present  in  transformer  core 
construction  and  is  superior  to  carbon  steel,  which  was  formerly 
used,  as  its  use  lowers  the  inital  core  loss  of  the  transformer,  which 
core  loss  remains  practically  constant  throughout  the  life  of  the 
transformer,  while  transformers  constructed  with  carbon  steel 
cores  have  higher  initial  core  loss,  which  loss  increases  with  the  age 
of  the  transformer  due  to  the  ageing  of  the  steel. 

4.  Coils  are  universally  built  of  insulated  wire  which  may  be  round, 
square  or  rectangular  in  cross  section.  The  latter  type  is  usually 

11  [  321  ] 


Sec.  6 


Coec:  Typf 


TRANSFORMERS 

Ceuc/roen  TYPE 


FIG.   149. — Types  of  transformer  cores. 


FIG.  150. — Secondary  winding  assei 
bled  on  cruciform  type  trans- 
former core. 


FIG.  151. — Cruciform  type  trans- 
former completely  assembled 
(ready  for  placing  in  case.) 


[  322  ] 


TRANSFORMERS  Sec.  6 

called  ribbon  wire.  In  small  transformers  of  the  cruciform  type 
(Fig.  150)  the  conductor  may  be  wound  directly  on  the  center 
leg  of  the  core,  or  the  coil  form  wound  and  then  assembled  on  the  iron. 

There  are  two  general  types  of  transformer  windings,  those  wound 
with  the  high  and  low  tension  elements  arranged  concentrically, 
and  with  these  elements  arranged  side  by  side.  The  latter  type  of 
winding  is  usually  referred  to  as  the  pancake  or  interleaved  winding. 
The  concentric  winding  is  usually  used  on  small  transformers  and 
the  latter  on  large  sizes.  Each  of  these  types  of  winding  can  be 
used  with  either  the  shell  type  of  construction  or  with  the  core  type. 

The  major  insulation  in  a  concentric  winding  consists  of  several 
large  pieces  of  mechanically  strong  insulating  material.  In  the 
pancake  or  interleaved  windings  there  is  relatively  a  larger  number 
of  small  pieces  of  insulating  material  required,  which,  when  thin 
or  fragile  material  is  used,  necessitates  careful  workmanship  in  order 
to  prevent  defects  in  the  finished  product. 


Oa.  DUCTS 


FIG.  152. — Core  type  coils  assembled. 

Small  transformers  with  concentric  type  windings  are  more 
easily  insulated  than  the  pancake  type  of  similar  sizes;  while  large 
capacity  pancake  type  windings  have  better  mechanical  prop- 
erties than  the  concentric  type. 

Form  wound  coils  are  generally  used  on  core  type  transformers 
although  under  some  conditions  it  is  possible  to  wind  the  copper 
directly  on  the  core.  In  the  larger  capacity  and  higher  voltage 
transformers  of  both  the  core  and  the  shell  type,  form  wound  coils 
are  universally  used. 

Core  type  transformers  have  also  been  constructed  of  a  number 
of  flat  formed  coils  (Fig.  153)  which  construction  facilitates  assem- 
bling and  insulation,  as  well  as  lending  itself  naturally  to  a  more 
rugged  construction  in  resisting  strains  due  to  abnormal  operating 
conditions.  It  also  permits  the  replacing  of  burnt-out  coils  at 
greatly  reduced  costs. 

Transformer  coils  should  be  designed  so  that  the  voltage  between 
layers  will  be  as  low  as  possible.  Also  the  insulation  should  be  such 

[  323  ] 


Sec.  6 


TRANSFORMERS 


that  high  factors  of  safety  will  be  assured,  as  electrical  disturbances 
may  subject  it  to  momentary  voltages  many  times  higher  than 
the  normal  voltage  of  operation.  The  usual  range  of  voltage  be- 
tween turns  is  from  0.5  to  10  volts  and  between  layers  from  100 
to  300  volts.  The  puncture  voltage  value  between  turns  should 
be  from  800  to  1500  volts  and  between  layers  from  1500  to  3000 
volts.  These  values  vary  with  design  and  type  of  transformer. 

In  order  to  prevent  an  abnormal  temperature  rise  in  the  trans- 
former when  in  operation,  oil  ducts  (Fig.  152)  are  generally  located 
between  the  transformer  coils  and  the  core,  and  between  the  various 


FIG.  153. — Interior  view  of  core  type  transformer 
wound  with  flat  formed  coils. 

sections  of  the  transformer  windings.  These  ducts  permit  the  circu- 
lation of  the  transformer  oil,  which  circulation  prevents  abnormal 
heating.  In  transformers  of  the  smaller  type  oil  ducts  are  seldom 
required,  as  the  volume  of  oil  surrounding  the;  coil  is  usually  suf- 
ficient to  carry  off  the  heat,  thus  preventing  an  abnormal  temper- 
ature rise. 

5.  Cases  are  made  of  either  .cast  iron  or  sheet  steel.  They  must 
be  oil  tight.  The  leading-in  bushings  should  have  sufficient  insu- 
lating strength  to  withstand  the  maximum  voltage  to  which  the 
transformer  may  be  subjected  and  also  should  be  water  tight.  The 
covers  are  usually  made  of  cast  iron  and  should  be  readily  re- 
movable. 

[324] 


TRANSFORMERS 


Sec.  6 


FIG.  154. — Self  cooling  out-door  type  transformer,  single-phase,  3,000  kv-a 
66,000/2,200  volts,  25  cycles. 

[325] 


Sec.  6 


TRANSFORMERS 


326] 


TRANSFORMERS  Sec.  6 

Experience  has  demonstrated  that  the  normal  exposed  surface  of 
the  containing  case  of  an  oil  immersed  transformer  does  not  provide 
sufficient  radiating  surface  for  transformers  larger  in  capacity  than 
25  kw.;  hence,  for  larger  sizes  the  transformer  cases  are  built  with 
corrugated  surfaces  which  increase  the  radiation  sufficiently  to 
prevent  an  abnormal  temperature  rise.  These  types  of  trans- 
former cases  are  shown  in  Figs.  154  to  161. 


FIG.  158. — Self  cooling  out-door  type  transformer,  single- 
phase,  33,000  volt  primary,  60  cyclea. 

TRANSFORMER  EQUATIONS 

6.  General.  An  ideal  transformer  should  convert  a  given  amount 
of  electrical  energy  at  a  given  voltage  and  frequency  to  the  same 
amount  of  electrical  energy  at  some  other  desired  voltage  and  the 
same  frequency;  should  completely  isolate  the  two  voltages,  and 
should  maintain  a  constant  electromotive  force  at  any  load,  pro- 
vided the  impressed  electromotive  force  is  constant.  (An  excep- 

[327] 


Sec.  6 


TRANSFORMERS 


tion  to  this  is  the  series  lighting  or  tub  transformer  which  maintains 
a  constant  current  at  all  loads.) 

Commercial  transformers  are  probably  the  most  perfect  energy 
converters  in  existence.  The  difference  between  the  energy  received 
and  the  energy  delivered  is  consumed  in  the  resistance  losses  of  the 


FIG.  159. — Self  cooling  out-door  type 

transformer,  three-phase,  100  kv-a, 

2.200/  220  volts,  60  cycles. 


FIG.  160. — Self  cooling  out-door  type 

transformer,  three-phase,  20  kv-a, 

2.200/  220  volts,  80  cycles. 


FIG.  161. — Self  cooling  out-door  type  transformers,  single  phase,  5-25  arid  100  kv-a, 

2,200/220  volts,  60  cycles.      (Illustrates  change  in  tank  construction  with 

increased  capacity.  ^ 

[  328  ] 


TRANSFORMERS  Sec.  6 

copper  windings  and  the  magnetic  losses  of  the  steel  core.  The 
magnetic  losses  are  those  due  to  hysteretic  and  eddy  current  phe- 
nomena. 

7.  Hysteretic  Losses.  Hysteresis  is  that  quality  of  a  magnetic 
substance  by  virtue  of  which  energy  is  dissipated  on  the  reversal 
of  its  magnetization.  For  a  given  quality  of  steel  this  loss  varies 
as  the  1.6  power  of  the  flux  density.  The  following  equations  for 
hysteretic  loss  have  been  determined  by  Dr.  Steinmetz 
Let 

Wi  =  the  power  in  watts  absorbed  by  hysteresis  in  the  steel 

core. 

V    =  the  volume  of  the  core  in  cubic  centimeters. 
f     =  the  frequency  in  cycles  per  second 
ft  max.  =  the  flux  density  in  lines  per  square  centimeter 

kh  =  the  co-efficient  of  hysteresis  depending  upon  the  quality 
of  steel. 

Then 


W 


107 


Values  of  kh  vary  from  0.0006  to  0.003,  depending  on  the  quality 
of  the  magnetic  material  and  such  values  are  experimentally  ob- 
tained. 

8.  Eddy  Current  Losses.  Eddy  current  losses  are  those  due 
to  the  induced  current  in  the  steel  laminations.  This  current  is 
produced  by  the  change  in  magnetic  flux,  which  induces  a  voltage 
in  the  laminations.  This  voltage  divided  by  the  impedance  of  the 
effective  circuit  in  each  lamination  determines  the  flow  of  current, 
the  square  of  which  times  the  resistance  will  give  the  loss  in  watts. 
Let 

Wa  =  the  power  in  watts  absorbed  by  eddy  currents  in  the 

steel  core. 

V    =  the  volume  of  the  core  in  cubic  centimeters. 
t     =  the  thickness  of  steel  sheets  in  centimeters. 
f     =  the  frequency  in  cycles  per  second. 
ft  max.  =  the  flux  density  in  lines  per  square  centimeter. 
ke   =  the  coefficient  of  eddy  current  loss. 


1011 

The  constant  ke  varies  with  the  specific  conductivity  of  the  core 
material  and  its  value  is  experimentally  determined.  A  fair  value 
being  approximately  0.65  for  silicon  steel. 

The  above  two  losses  produce  heat  in  the  steel  core  and  are  prac- 
tically constant  at  all  loads.  The  total  amount  of  energy  absorbed 
is  equal  to  the  sum  of  the  two  losses  and  can  be  determined  by  the 
following  equation. 

We  =  Wi+W2 

[  329  ] 


Sec.  6  TRANSFORMERS 

The  energy  component  of  the  no-load  transformer  current  is 
found  by  dividing  the  total  transformer  loss  in  watts  at  no-load 
by  the  transformer  voltage. 


9.  Copper  Losses.     Copper  loss  in  a  transformer  is  the  sum  of 
the  I2r  losses  in  both  the  primary  and  secondary  windings. 

Let 

Ii    =  the  load  current  in  the  primary  winding  in  amperes. 
TI    =  the  resistance  of  the  primary  winding  in  ohms. 
la    =  the  load  current  in  the  secondary  winding  in*  amperes. 
r«    =  the  resistance  in  the  secondary  winding  in  ohms. 
Wc  =  the  total  copper  loss  at  full  load  in  watts. 

Then 

Wc=r1I12  +r,W 

The  total  power  loss  at  full  load  is  the  sum  of  the  no-load  and  the 
full  load  losses,  therefore 

Wt-We+Wc 

in  which  We  is  a  constant  quantity  and  Wc  varies  with  the  square 
of  the  load  on  the  transformer. 

NOTE:  The  effect  of  the  loss  produced  by  the  no-load  current 
of  the  transformer  flowing  through  the  primary  resistance  has  been 
neglected  as  the  error  introduced  thereby  is  small.  However,  if 
it  is  desired  to  consider  it,  the  primary  current  Ii  may  be  corrected 
for  this  effect  by  adding  the  no-load  current  to  it  vectorially.  There 
is  a  small  loss  in  the  windings  aside  from  the  I2r  loss,  due  to  the  eddy 
currents,  which  are  caused  by  the  leakage  magnetic  flux. 

10.  Exciting  Current.     When  the  impressed  voltage  is  a  pure 
sine  wave,  the  wattless  component  of  the  no-load  current  is  never 
a  sine  wave.     This  deviation  from  a  sine  wave  is  caused  by  the 
variation  in  the  flux  density  curve  of  the  transformer  steel  and 
also  by  the  fact  that  the  increasing  and  decreasing  saturation  curves 
do  not  coincide.     In  ordinary  calculations  this  complexity  in  the 
wave  form  of  the  magnetizing  current  of  a  transformer  is  generally 
neglected  and  very  approximate  calculations  are  based  on  a  pure 
sine  wave.     With  this  assumption,  the  fundamental  equation  of 
magnetic  relations  is  quite  simple. 

Let 

!>  max-  =  the  total  maximum  magnetic  flux. 

N  =  the  total  number  of  turns  on  the  transformer  primary 

winding. 
Im  =  the  effective  value  of  the  magnetizing   current  in  am- 

peres. 

A    =  the  area  of  the  core  in  square  centimeters. 
1    =  the  length  of  the  magnetic  circuit  in  centimeters. 
n     =  the  permeability  of  the  iron. 

[330] 


TRANSFORMERS  Sec.  6 

Then 

4  TT  N  ImV2  A  /z     1.26  N  ImV2  A  /* 

-   --  — 


Therefore 

10  0  max  1  10  0   max    1 


4  TT  V2  N  /x    4  TT  V  2  A  N  M 

The  exciting  current  of  the  transformer  is  found  by  combining 
the  quadrature  vector  sum  of  the  power  and  wattless  components. 
Thus 

Ie  =   Vlc2-flm2 

The  no-load  power  factor  of  the  transformer  is  found  by  dividing 
the  energy  component  of  the  current  by  the  total  exciting  current. 
Thus 

Cos.  9'=A 

le 

11.  Induced  Voltage.  The  calculation  of  the  ratio  between 
the  impressed  electromotive  force  and  the  counter  electromotive 
force  of  the  transformer  winding  is  dependent  upon  the  reactance 
and  resistance  drops  in  the  transformer  primary  winding.  This 
difference  is  usually  a  few  percent  and  the  method  of  deter- 
mining it  is  given  in  Section  7,  Article  49.  The  relations  between 
the  counter  electromotive  force  of  the  transformer  coil  and  the 
various  factors,  such  as  flux  density,  number  of  turns,  frequencies, 
etc.,  are  determined  by  the  following  formuke.  These  equations 
are  based  on  the  assumption  that  the  electromotive  force  is  a  true 
sine  wave  and  are  the  most  important  formulae  used  in  the  design 
of  transformers. 

Let 

E     =  the  effective  induced  electromotive  force  in  volts. 
</>   max-  =  the  total  magnetic  flux. 
/3   max.  =  the  lines  of  magnetic  flux  per  square  inch. 

A     =  the   cross  section  of  the   magnetic   circuit   in  square 

inches. 
N     =  the  total  number  of  turns  on  the  transformer  primary 

winding. 

f       =  the  frequency  in  cycles  per  second. 
Then 

E      =    27rfJN0  max  ^4.44  f  N<ftmax 

V2~108  1Q8 

also 

27rfNA/3max  4.44fNA/3max 


E 


V2  108 

[331] 


Sec.  6  TRANSFORMERS 

From  these  equations  it  is  possible  to  determine  any  one  of  the 
unknown  values  when  the  remaining  values  are  given.  Magnetic 
densities  in  the  transformer  core  vary  over  wide  ranges.  In  modern 
practice  the  following  values  are  in  general  use. 

For  25  or  60  cycle  transformers  —  densities  of  from  40,000  to 
90,000  C.  G.  S.  lines  per  square  inch. 

The  current  density  in  the  copper  winding  is  limited  by  the  ability 
of  the  transformer  to  dissipate  the  heat  generated  therein.  The 
radiation  in  turn  will  be  affected  by  the  design  of  the  ^  transformer. 

12.  Ratio  of  a  voltage  or  of  a  power  transformer  is  the  ratio  of 
the  r.m.s.  primary  terminal  voltage  to  the  r.m.s.  secondary  terminal 
voltage  at  rated  load,  approximately  sinusoidal  voltage  assumed. 
The  Ratio  of  a  current  transformer  is  the  ratio  of  r.m.s.  primary 
current  to  r.m.s.  secondary  current,  at  rated  load,  approximately 
sinusoidal  currents  assumed. 

NOTE  :  In  many  practical  cases,  particularly  in  the  case  of  power 
transformers,  it  is  a  sufficient  approximation  to  take  the  ratio  as 
the  ratio  of  turns,  and  it  is  this  ratio  that  is  ordinarily  given  on  the 
name  plate  of  power  transformers.  To  specify  a  precise  ratio  for 
a  given  transformer,  as  may  be  desirable  in  the  case  of  instrument 
transformers,  it  is  necessary  to  specify  frequency,  wave  form,  voltage 
(or  current,  in  the  case  of  the  current  transformers)  load,  and  power 
factor  of  the  load. 

Let 

Ep  =  the  primary  voltage  in  volts. 

Es  =  the  secondary  voltage  in  volts. 

Np  =  the  primary  turns  on  the  transformer. 

N8  =  the  secondary  turns  on  the  transformer. 

Ip  =  the  primary  current  in  amperes. 

Is    =  the  secondary  current  in  amperes. 

n     =  transformer  ratio. 

Then  from  Section  6,  Article  11. 

Ep  =  K  Np 
Es  =  K  N. 

n     _Ep_Np 

~- 


Therefore 

.^  =  A=n=Np 
E9      Ip  Ns 

The  above  assumes  that  the  ratio  is  equal  to  the  ratio  of  turns 
in  the  primary  and  secondary  windings. 

13.  Equivalent  Resistance  and  Reactance  of  Transformer  Coils. 
In  making  calculations,  it  is  often  convenient  to  use  the  total  equiv- 
alent resistance  and  reactance  of  a  transformer  rather  than  to 

[332] 


TRANSFORMERS  Sec.  6 

make  two  calculations  utilizing  the  primary  and  secondary  reac- 
tances and  resistances  separately.  This  total  reactance  and  re- 
s'stance  may  be  found  in  the  following  manner: 

Ep  =  primary  voltage  (assumed  to  be  the  high  voltage  side). 

Es  =  secondary  voltage. 

Ip  =  primary  current. 

Is    =  secondary  current. 

n    =  ratio  of  transformation. 

rp   =  primary  resistance. 

rs    =  secondary  resistance. 

i'sp  =  secondary  resistance  referred  to  the  primary. 

rt    =  total  resistance  referred  to  the  primary. 

xp  =  primary  reactance. 

xs    =  secondary  resistance. 

xsp  =  secondary  reactance  referred  to  the  primary. 

xt   =  total  reactance  referred  to  the  primary. 

Then  neglecting  magnetizing  current 
I8    =  n  Ip 

Es  =^ 
n 

The  secondary  percent  voltage  drop  in  terms  of  the  equivalent 
primary  voltage  drop  must  be  equal  to  the  secondary  percent  voltage 
drop.  Therefore 

*       rsp  Ip 

~~ 


rsp  =  rs  n2 
Similarly 

xsp  =  xs  n2 

rt    =  rp+rsp=rp4-n2  rs 

xt    =  xp-|-xsp  =  Xp+n2  xg 

14.  FEATURES  OF  DESIGN.     The  design  of   transformers  is 

affected  primarily  by  the  ultimate  cost  which  is  governed  by  several 

conditions,  the  most  important  of  which  are: 

1st.     The  quality  of  the  insulation  between  the  primary  and 

secondary  windings.     (Art.  15.) 

2nd.     The  allowable  temperature  rise  in  the  transformer  during 

operation.     (Art.  16.) 

3rd.     The  efficiency  of  the  transformer.     (Art.  17.) 

4th.     The  regulation  of  the  transformer.     (Art.  18.) 

5th.     Limiting  the  "ageing"  of  transformer  cores.     (Art.  19.) 

[  333  ] 


Sec.  6  TRANSFORMERS 

6th.     The  power-factor  and  the  exciting  current.     (Art.  20.) 

15.  Insulation.     No   feature   of   transformer   design   should    be 
given  more  attention  than  the  insulation,  as  on  the  quality  and 
durability  of  this  depends  the  life  of  the  transformer.     Aside  from 
its  initial  excellence,  the  insulation  should  preserve  all  its  properties 
after  years  of  continuous  use,  having  been  subjected,  in  the  interim, 
to  heavy  overloads  and  high  temperatures  for  short  periods. 

Insulation  may  be  divided  into  four  classes: 

1st.  Fibrous  materials,  such  as  paper  and  cloth,  which  are  used 
principally  between  the  layers  of  wire. 

2nd.     Fireproof  insulation,  such  as  Mica  or  Asbestos. 

3rd.     Impregnating  compounds. 

4th.     Transformer  oil. 

Of  the  above  insulations  Mica  and  varnished  cloth  are  the  most 
used.  Mica,  because  of  its  high  dielectric  strength  and  fireproof 
quality,  is  particularly  efficient  but  where  short  turns  must  be  made, 
it  is  difficult  to  apply,  as  it  is  mechanically  weak.  The  flexibility 
of  varnished  cloth,  together  with  the  ease  with  which  it  may  be  ap- 
plied, makes  its  use  in  transformer  insulation  very  general.  The  other 
materials  given  are,  as  a  rule,  lower  in  dielectric  strength.  They 
are  used  to  a  considerable  extent  but  usually  in  places  where  mechan- 
ical separation  rather  then  electrical  insulation  is  desired. 

In  the  application  of  these  insulating  materials  we  may  distin- 
guish between  two  general  methods  of  insulation. 

1st.     The  Impregnation  Method. 

2nd.     The  Varnish  Method. 

The  first  method  is  used  with  small  windings  of  a  large  number 
of  turns.  The  entire  winding  is  impregnated  with  a  compound 
which  solidifies  at  ordinary  temperatures.  Only  untreated  material 
is  used  with  this  treatment,  as  treated  insulation  would  keep  out 
the  impregnating  compound. 

The  second  type  of  insulation  is  used  for  large  windings  of  rela- 
tively large  wire  and  few  number  of  turns.  Treated  material  is 
used  freely,  as  for  instance,  varnished  cloth.  The  various  parts 
of  the  windings  are  dipped  in  varnish  and  baked. 

16.  Temperature.*     There  are  two  methods  in  common  use  for 
determining    the  rise  in  temperature,  viz.:    (1)  by  thermometer, 
and  (2)  by  increase  in  resistance  of  an  electric  circuit. 

The  temperature  of  electrical  machinery  under  regular  service 
conditions,  should  never  be  allowed  to  remain  at  a  point  at  which 
permanent  deterioration  of  its  insulating  material  takes  place. 

It  is  recommended  that  the  following  maximum  values  of  tem- 
perature elevation,  referred  to  a  standard  room  temperature  of 
25  degrees  centigrade,  at  rated  load  under  normal  conditions  of 
ventilation  or  cooling,  should  not  be  exceeded. 

Transformers    for    Continuous    Service.     The    temperature    rise 

*A.I.E.E.  rules  are  in  the  process  of  revision.  Revised  rules  should  be  used 
instead  of  above. 

[  334.] 


TRANSFORMERS  Sec.  6 

should  not  exceed  50  deg.  Cent,  in  electric  circuits,  by  resistance; 
and  in  other  parts,  by  thermometer. 

Transformers  for  Intermittent  Service.  In  the  case  of  trans- 
formers intended  for  intermittent  service,  or  not  operating  contin- 
uously at  rated  load,  but  continuously  in  circuit,  as  in  the  ordinary 
case  of  lighting  transformers,  the  temperature  elevation  above  the 
surrounding  air-temperature  should  not  exceed  50  deg.  Cent.,  by 
resistance  in  electric  circuits  and  by  thermometer  in  other  parts, 
after  the  period  corresponding  to  the  term  of  rated  load.  In  this 
instance,  the  test  load  should  not  be  applied  until  the  transformer 
has  been  in  circuit  for  a  sufficient  time  to  attain  the  temperature 
elevation  due  to  core  loss.  With  transformers  for  commercial 
lighting,  the  duration  of  the  rated-load  test  may  be  taken  as  three 
hours,  unless  otherwise  specified. 

Reactors,  Induction-  and  Magneto-Regulators.  Electric  circuits 
by  resistance  and  other  parts  by  thermometer,  50  deg.  Cent. 

Large  Apparatus.  Large  generators,  motors,  transformers,  or 
other  apparatus  in  which  reliability  and  reserve  overload  capacity 
are  important,  are  frequently  specified  not  to  rise  in  temperature 
more  than  40  deg.  Cent,  under  rated  load  and  55  deg.  Cent,  at  rated 
overload.  It  is,  however,  ordinarily  undesirable  to  specify  lower 
temperature  elevations  than  40  deg.  Cent,  at  rated  load,  measured 
as  above. 

The  maintenance  of  low  temperature  in  a  transformer  is  desirable, 
as  it  prevents  the  ageing  tendency  of  steel  and  the  deterioration 
of  the  insulation.  Statements  regarding  temperature  rise,  however, 
and  the  method  of  its  determination  are  meaningless  unless  all 
the  varying  conditions  attached  thereto  are  considered.  Measure- 
ments made  by  a  thermometer  to  determine  coil  temperature  are 
usually  of  little  value.  There  is  little  possibility  of  local  high  tem- 
perature in  any  part  of  the  winding  of  a  small  transformer  where 
the  ratio  of  the  energy  loss  to  the  radiating  surface  is  small.  In 
large  transformers,  however,  the  number  of  watts  radiated  per 
square  inch  of  radiating  surface  is  considerably  greater,  and  sections 
of  the  winding  may  be  at  a  considerably  higher  temperature  than 
thermometer  measurements  would  indicate.  Transformers  of  this 
type  are  usually  provided  with  a  liberal  number  of  ventilating  ducts 
located  between  the  sections  of  the  winding  and  between  the  wind- 
ings and  the  core,  which  ducts  facilitate  the  circulation  of  the  oil. 
Corrugated  transformer  cases  increase  the  radiating  surface. 

Transformers  for  pole  line  use  are  usually  self-cooling.  Trans- 
formers for  out-of-door  sub-stations  are  also  generally  self-cooling. 

17.  Efficiency.  The  efficiency  of  an  apparatus  is  the  ratio  of 
its  output  to  its  input.  The  output  and  input  may  be  in  terms  of 
watt-hours,  watts,  volt-amperes,  amperes,  or  any  other  quantity 
of  interest,  thus  respectively  defining  energy-efficiency,  power- 
efficiency,  apparent-power-efficiency,  current-efficiency,  etc.  Unless 
otherwise  specified,  however,  the  term  is  ordinarily  assumed  to  refer 
to  power-efficiency. 

[  335  ] 


Sec.  6  TRANSFORMERS 

Apparent  Efficiency.  In  apparatus  in  which  a  phase  displacement 
is  inherent  to  their  operation,  apparent  efficiency  should  be  under- 
stood as  the  ratio  of  net  power  output  to  volt-ampere  input. 

a.  NOTE.     Such    apparatus    comprises    induction    motors,    syn- 
chronous phase  modifiers,   synchronous  converters  controlling  the 
voltage    of    an    alternating-current    system,    potential    regulators, 
open  magnetic  circuit  transformers,  etc. 

b.  NOTE.     Since  the  apparent  efficiency  of  apparatus  delivering 
electric  power  depends  upon  the  power-factor  of  the  load,  the  appar- 
ent efficiency  unless  otherwise  specified  should  be  referred  to  a  load 
power-factor  of  unity. 

In  Stationary  Induction  Apparatus,  the  losses  are: 

a.  Molecular  Magnetic  Friction  and  Eddy   Currents  measured 
at   open  secondary  circuit,  rated  frequency,  and  at  rated  voltage 
—I  r,  where  I.= rated  current,  r=resistance  of  primary  circuit. 

b.  Resistance  Losses,  the  sum  of  the  I2  r  losses  in  the  primary 
and  in  the  secondary  windings  of  a  transformer,  or  in  the  two  sections 
of  the  coil  in  a  compensator  or  auto-transformer,  where  I  =  rated 
current  in  the  coil  or  section  of  coil,  and  r  =  resistance. 

c.  Load  Losses,  i.e.,  eddy  currents  in  the  iron  and  especially  in 
the  copper  conductors,  caused  by  the  current  at  rated  load.     For 
practical  purposes  they  may  be  determined  by  short-circuiting  the 
secondary  of  the  transformer  and  impressing  upon  the  primary 
a  voltage  sufficient  to  send  rated  load  current  through  the  trans- 
former.    The  loss  in  the  transformer  under  these  conditions,  meas- 
ured by  wattmeter,  gives  the  load  losses  -fP  r  losses  in  both  primary 
and  secondary  coils. 

In  Closed  Magnetic  Circuit  Transformers,  either  of  the  two 
circuits  may  be  used  as  primary  when  determining  the  efficiency. 

In  Potential  Regulators,  the  efficiency  should  be  taken  at  the 
maximum  voltage  for  which  the  apparatus  is  designed,  and  with  non- 
inductive  load,  unless  otherwise  specified. 

The  usual  method  of  determining  the  efficiency  at  full  load  is 
to  divide  the  full  load  output  by  the  full  load  output,  plus  the  sum 
of  the  power  measured  on  open  circuit  test  (core  loss)  and  on  short 
circuit  test  (copper  loss). 

Let 

17     =  the  efficiency  of  the  transformer  in  percent. 

W  =  the  power  output  of  the  transformer  in  watts  at  full  load. 

we  =  the  iron  losses  in  watts. 

wc  =  the  copper  losses  at  full  load  in  watts. 

Then 

100  W 
77   ~  W+We+wc 

18.  Regulation.  The  regulation  of  a  machine  or  apparatus  in 
regard  to  some  characteristic  quantity  (such  as  terminal  voltage 
or  speed)  is  the  change  in  that  quantity  between  any  two  loads. 
Unless  otherwise  specified,  the  two  loads  considered  shall  be  zero 

r  336  1 


TRANSFORMERS  Sec.  6 

load  and  normal  rated  load.  The  regulation  may  be  expressed  by 
stating  the  numerical  values  of  the  quantity  at  the  two  loads,  or  it 
may  be  expressed  as  the  ratio  of  the  change  in  the  quantity  to  the 
value  of  the  quantity  considered  as  normal  for  the  machine  or 
apparatus. 

In  constant  potential  transformers,  the  regulation  is  the  difference 
between  the  no-load  and  rated  load  values  of  the  secondary  terminal 
voltage  at  the  specified  power-factor  (witl  constant  primary  im- 
pressed terminal  voltage)  expressed  in  percent  M  the  rated  load  sec- 
ondary voltage. 

NOTE:  The  rated  current  of  a  constant  potential  transformer 
is  that  secondary  current  which,  multiplied  by  the  full-load  secon- 
dary voltage,  gives  the  kv-a.  rated  output.  That  is,  a  transformer 
of  given  kv-a.  rating  must  be  capable  of  delivering  the  rated  out- 
put at  constant  secondary  voltage,  while  the  primary  impressed 
voltage  is  increased  to  whatever  value  is  necessary  to  give  constant 
secondary  voltage. 

19.  Magnetic  Fatigue  or  the  Ageing  of  Steel.  Transformer  core 
loss  may  increase — due  to  the  ageing  of  the  steel  in  the  transformer 
coil,  particularly  where  the  core  has  been  continually  subjected 
to  abnormal  operating  temperatures. 

While  the  cause  of  this  phenomena  has  not  been  discovered, 
several  very  important  conclusions  have  been  drawn  as  the  result 
of  investigation  by  Mr.  W.  E.  Goldsborough,  Mr,  Wm.  M.  Mordey 
and  Mr.  S.  R.  Rouget. 

1st.  Steel  and  iron  when  maintained  at  the  same  temperature, 
show  very  great  hysteretic  differences,  depending  upon  the  quality 
of  the  material. 

2nd.  The  increase  in  the  hysteretic  loss  of  a  given  volume  of 
iron  or  steel  is  dependent  upon  the  temperature  at  which  it  is 
maintained. 

3rd.  Within  ordinary  temperature  ranges  fche  variation  in  this 
loss,  due  to  ageing,  increases  with  the  temperature. 

4th.     Soft  sheet  steel  is  less  subject  to  ageing  than  soft  sheet  iron. 

5th.  Sheet  steel  that  does  not  age  materially  at  temperatures 
below  75°  C.  can  be  obtained,  but  almost  any  iron  or  steel  ages 
more  or  less  at  high  temperatures.  Silicon  steel  is  practically 
non-ageing  at  working  temperatures. 

The  values  in  Fig.  162  illustrate  the  results  of  a  test  made  by 
Prof.  Goldsborough,  Purdue  University,  on  five  transformers  and 
show  the  increase  in  transformer  core  loss  due  to  ageing. 

Figs.  163  and  164  illustrate  the  change  in  the  core  loss  in  steel 
after  prolonged  heating. 

Fig.  165  illustrates  the  change  in  hysteretic  loss  due  to  ageing 
and  illustrates: 

1st.     The  original  hysteretic  loss  of  the  transformer. 

2nd.  The  effect  of  baking  the  core  for  nineteen  (19)  hours  in 
a  temperature  of  200°  C.,  indicating  that  after  such  a  treatment 
the  hysteretic  loss  has  greatly  increased. 

[337] 


Sec.  6 


TRANSFORMERS 


/01 


" 


<M 


V 


O      S     /O      /S    20     2, 'S    30     3S     40    4S     60    S5 


FIG.  162. — Illxistrates  the  increase  in  iron  loss  due  to  ageing  (tests  made  on 
5  transformers.) 


IW 

k  '* 

^B   70 

|l   *° 
§£  *> 

fc      30 
20 
/O 
0  ' 

ft 

/    ^ 

\^ 

*^. 

^  

/ 

f 

\ 

X 

1 

I 

/ 

/ 

/ 

"0      /O     20    30    40    SO     60     70     SO     W     100   HO    I2C 

FIQ.  163. — Increase  in  hysteretio  loss  of  iron  due  to  continued  heating. 
[338] 


TRANSFORMERS 


Sec.  6 


3rd.  The  effect  of  baking  the  core  for  four  days  in  a  temperature 
of  200°  C.,  indicating  a  decrease  in  hysteretic  loss  which  would  seem 
to  show  that  prolonged  heating  is  productive  to  partial  recovery  in 
permeability. 


200\ 


I    I   I   I    I   I   I    I    I    I   I    I    I   I    I 


AG&MG  rcsr  ON  SAMPLES  or  IROM 

Ur  FROM  TH£3An£3He£T  Of  M£ 
H£AT£D  TO  DtrrceENT  T£MP£eATU8£3 


FIG.  164. 


Fia.  165. 
[339] 


Sec.  6  TRANSFORMERS 

20.  Power-Factor  and  Reactive  Factor.  The  power-factor  in 
alternating-current  circuits  or  apparatus  is  the  ratio  of  the  effective 
(i.e.  the  cyclic  average)  power  in  watts  to  the  apparent  power  in 
volt-amperes.  It  may  be  expressed  as  follows: 

effective  power  _    effective  watts    _  effective  current  _ 
apparent  power  ~~  total  volt-amperes  ~"    total  current 
effective  voltage 

total  voltage 

The  Reactive-Factor  is  the  ratio  of  the  reactive  volt-amperes 
(i.e.,  the  product  of  the  reactive  component  of  current  by  voltage, 
or  reactive  component  of  voltage  by  current)  to  the  total  volt- 
amperes.  It  may  be  expressed  as  follows: 

reactive  power  _     reactive  watts     _  reactive  current  _ 
apparent  power    total  volt-amperes       total  current 
reactive  voltage 
total  voltage 

Power-Factor  and  Reactive-Factor  are  related  as  follows: 
If  p  =  power-factor  and  q  =  reactive-factor,  then  with  sine  waves 
of  voltage  and  current, 

pz+q*  =  l 

With  distorted  waves  of  voltage  and  current,  q  ceases  to  have 
definite  significance. 

It  will  be  noted  that  for  sine  waves  the  relation  between  the 
apparent  power  and  the  effective  power  is  a  cosine  relation,  thus 
for  power-factors  of  circuits  in  which  the  shape  of  the  voltage  and 
current  waves  are  a  true  sine,  cos.  0  may  be  used  to  designate  the 
power-factor  of  the  circuit  and  6  to  designate  the  power-factor 
angle. 
Let 

cos. 9    =  the  power-factor  of  the  load. 

cos.O'  =  the  power-factor  of  the  transformer. 

W         =  the  power  output  of  the  transformer  in  watts. 

We         =  the  core  loss  of  the  transformer  in  watts. 

wc         =  the  copper  loss  of  the  transformer  in  watts. 

Im         =  the  magnetizing  current  of  the  transformer. 

Io          =  the  load  current  of  the  transformer  at  power-factor, 

cos.9. 

E          =  the  effective  primary  voltage  of  the  transformer, 
xt          =  the   reactance    of    the    transformer   referred   to    the 

primary. 
Then 

T       ft'  -  E  Im+xtIo2+Wtan.e 
ian.  o  —    • 

W+We+Wc 

values  of  tan.6  may  be  found  for  values  of  cos.O  from  the  trigono- 
metric tables  in  Section  1. 

[  34o  ] 


TRANSFORMERS 


Sec.  6 


ffi 

/ 

/ 

1 

J/ 

1 

REGULATION  AT  100  %  RK-  2.10% 
»        »  80%  »  -230% 

\\ 

A 

1 

EXCITING  CUMENTX/OO  . 

••3.00% 

x 

I 

FULL  LOAD  CUWENT 

^ 

X 

1 

X 

J 

/ 

..^ 

0 

^ 

•^ 

^/ 

J 

Tn 

^ 

•^ 

^x 

X 

1 

TO 

0^, 

X 

J 

^- 

-^-- 

rn 

p^l 

H- 

= 

—  • 

•^ 

^ 

M\ 

^ 

Lt(. 

^_ 

"M 

^ 

** 

i 

,^-- 

-^ 

oLL. 

•• 

e= 

— 

—  — 

— 

^7  Zf  JJ7  %LOAD     15  100 

3  K.V.A.TnANsroenci?  60  Cracs 

Z20O  VOLTS  PeiriAKr          220///0  VOLTS  SECONDARY 

Fio.  166. 


REGULATION  AT  100  %  RK-t 

»80%  »  "Z.SS% 
EXCITING  CUWENTX/OO  _ 
FULL  LOAD  CUWENT  ~' 


JO  %LOAD     7S 

2200  VOLTS PeinARr  220//lOVoLTS~SKONDMr 

Fia.  167. 
[341] 


Sec.  6 

lOOr 


TRANSFORMERS 


2S  SO   %LOAD     15  100 

SO  K.V.A.TRANsroerice  60  CYCLES 

2200  VOLTS Pei n Mir  220/110  VOLTS  SECONDARY 

FIG.  168. 


125 


4200 


80%  »  "2.40% 
EXCITING  CUWENT 'x  /OO  _,  ^ 
FULL  LOAD  CUPPENT  =  ~ 


^ 


ISOO 
1200 
bOO 


2S  SO   %LOAD     15  100 

200 K.V.A.TRANsroenEi?  60  CYCLES 

2200  VOLTS  PpinAur  220/ffO  VOL  rs  SECONOAP? 

FIG.  169. 
[342] 


KS 


TRANSFORMERS 


Sec.  6 


240 


GSUUmtf  AT  100%  R£>-4J8  % 
»       »  80%  »  =4.14  % 

fyctTtM  CURRENT  x  100   - 


0  25  JO   %LOAD     75 

2200  VOLTS  PRIMARY  220///0  VOLTS  SECONDARY 

FIG.  170. 


an 

p 

^s 

Of) 

' 

7/7 

^ 

1400 

REGULATION  AT  100  %  RK 

>•  80%  »  ' 
EXCITING  CURRENTX/OO  , 

-t.7S% 

^/ 

^ 

* 

66 

x 

/ 

innn 

FULL  LOAD  CURRENT 

/ 

? 

2 

/ 

x 

fnn 

X 

? 

x 

4(j 

\ 

ui 

x 

X 

n 

9* 

\ 

& 

X 

Jo 

^ 

•^ 

r 

9* 

y 

400 
200. 

Q 

f 

20 

-  -—• 

K= 

= 

—  - 

—  - 

~ 

^. 

~ 

/p. 

^ 

.^. 

J 

^— 

^ 

•^ 

^ 

•^ 

0 

—  — 

—  = 

=: 

.  — 
2 

—  -~ 
5 

s 

T 

%L 

~A 

0 

~i 

5 

« 

7 

& 

FIG.  171. 
[  343  ] 


Sec.  6 


TRANSFORMERS 


100 

on 

X 

P"*^ 

w 

** 

tt- 

/ 

Xn 

X 

7/1 

X 

REGULATION  AT  100%  RE 
»        »  80%  >•  ' 
EXCITING  CuwENTxIOO  . 

^ 

/ 

? 

/ 

j 

/ 

y  ^ 

FULL  LOAD  CUWENT 

x 

^ 

^ 

/ 

/ 

AH 

" 

X 

J 

X 

U° 

?^l 

7 

I 

10 

X 

— 

(( 

p!x 

^ 

JL 

-^ 

*.  —  • 

***" 

* 

fff 

V 

>1 

J 

x 

^ 

^ 

^ 

^^ 

**' 

0 
Wr- 

U-KT1   1   1  1  1  1  1  1  1  1  1  1  1  1  1   1  1   II 

25                 JO   %LOAD     75                  100                 /£ 
SO  K.V.AJRANsroeriEK               60  CrcLCs 
6600  VOLTS  PeinAKr             Z20//IO  VOL  rs  SecoNDAer 

FIG.  172. 

\    Y 

J( 

/ 

M 

^x 

TU 

REGULATION  AT  100  %  f>F.~/.SO  % 
»  80%  "  "3.20% 

x 

-ill 

^ 

X 

TP 

EXCITING  CUWENTX/OO  _ 

^ 

^ 

J 

FULL  LOAD  CUWENT 

^ 

/ 

1 

x 

,s 

4J\ 

x 

' 

X 

•M 

l,u 

i> 

, 

X 

u 

5 

X 

JC1  — 

•— 

•** 

X 

^ 

ff? 

L|i 

!>• 

o 

i^. 

-" 

-'    *  •- 

K= 

= 

** 

.—  - 

2f  JO   %LOAD     15 

SO  IWAJnAHsroenEi? 
13200  VOLTS  PeinAKr  220/1/0 

FIG.  173. 
[344] 


IZS 


TRANSFORMERS  Sec.  6 

Values  of  the  power-factor  of  the  transformer  on  the  primary  side 
cos.O'  may  be  found  from  values  of  tan. 6'  in  the  trigonometric 
tables  in  Section  1. 

At  no-load  tan.6'0=5JE 
wc 

21.  Transformer    Characteristics.     Figs.    166    to    173    inclusive 
illustrate  the  average  characteristic   of    transformers    for  use  on 
2200,  6600  and  13,200  volt  systems.     The  characteristics  of  trans- 
formers ranging  in  potential  from  22,000  to  66,000  volts  will  vary 
approximately  as  follows: 

The  efficiency  will  vary  with  the  kv-a.  rating,  and  inversely  with 
the  voltage. 

The  regulation  at  100%  P.F.,  resistance  drop  and  exciting  current, 
will  vary  with  the  voltage  and  inversely  with  the  kv-a.  rating. 
The  reactance  drop  will  vary  from  3  to  8  percent  and  the  regulation 
at  80  P.F.  from  2^  to  Q}4  percent,  depending  upon  the  kv-a.  rating, 
voltage  and  frequency.  The  power-factor  at  no  load  will  vary  be- 
tween the  limits  of  12  and  30  percent. 

22.  TRANSFORMER   TESTING.      The    following   transformer 
tests  are  not  intended  to  illustrate  shop  practice,  but  are  included 
as  the  simple   accurate    tests  which  may  be  made  by  operating 
companies. 


1st. 
2nd. 
3rd. 
4th. 
5th. 
6th. 
7th. 
8th. 
9th. 

Insulation. 
Heating. 
Core  loss  and  exciting  current. 
Resistance. 
Copper  loss. 
Reactance  Drop. 
Regulation. 
Ratio. 
Polarity. 

(Art.  23.) 
(Art.  24.) 
(Art.  25.) 
(Art.  26.) 
(Art.  27.) 
(Art.  28.) 
(Art.  29.) 
(Art.  30.) 
(Art.  31.) 

23.  INSULATION.* 

(I)    INSULATION  RESISTANCE. 

Insulation  Resistance  is  the  ohmic  resistance  offered  by  an  in- 
sulating coating,  cover,  material  or  support  to  an  impressed  voltage, 
tending  to  produce  a  leakage  of  current  through  the  same. 

Ohmic  Resistance  and  Dielectric  Strength.  The  ohmic  resis- 
tance of  the  insulation  is  of  secondary  importance  only,  as  compared 
with  the  dielectric  strength  or  resistance  to  rupture  by  high  voltage. 
Since  the  ohmic  resistance  of  the  insulation  can  be  very  greatly 
increased  by  baking,  but  the  dielectric  strength  is  liable  to  be  weak- 
ened thereby,  it  is  preferable  to  specify  a  high  dielectric  strength 
rather  than  a  high  insulation  resistance.  The  high-voltage  test  for 
dielectric  strength  should  always  be  applied. 

*A.  I.  E.  E.  rules  are  in  the  process  of  revision.  Revised  rules  should  be  used 
instead  of  above. 

[345] 


Sec.  6 


TRANSFORMERS 


Recommended  Value  of  Resistance.     The  insulation  resistance 
of  completed  apparatus  should  be  such  that  the  rated  terminal 


voltage  of  the  apparatus  will  not  send  more  than 


of  the 


1,000,000 

rated-load  current,  through  the  insulation.     Where  the  value  found 
in  this  way  exceeds  one  megohm,  it  is  usually  sufficient. 

Insulation  Resistance  Tests  should,  if  possible,  be  made  at  the 
pressure  for  which  the  apparatus  is  designed. 

(II)    DIELECTRIC  STRENGTH. 

Test  Voltages. 

Definition.  The  dielectric  strength  of  an  insulating  wall,  coating, 
cover  or  path  is  measured  by  the  voltage  which  must  be  applied  to  it 
in  order  to  effect  a  disruptive  discharge  through  the  same. 

Basis  for  Determining  Test  Voltages.  The  test  voltage  which 
should  be  applied  to  determine  the  suitability  of  insulation  for 
commercial  operation  is  dependent  upon  the  kind  and  size  of  the 
apparatus  and  its  normal  operating  voltage,  upon  the  nature  of  the 
service  in  which  it  is  to  be  used,  and  the  severity  of  the  mechanical 


FIG.  174. — Insulation  test.      (Using  special  testing  transformer.) 

and  electrical  stresses  to  which  it  may  be  subjected.  The  voltages 
and  other  conditions  of  test  which  are  recommended  have  been  de- 
termined as  reasonable  and  proper  for  the  great  majority  of  cases 
and  are  proposed  for  general  adoption,  except  when  specific  reasons 
make  a  modification  desirable. 

Condition  of  Apparatus  to  be  Tested.  Commercial  tests  should, 
in  general,  be  made  with  the  completely  assembled  apparatus  and 
not  with  individual  parts.  The  apparatus  should  be  in  good  con- 
dition and  high- voltage  tests,  unless  otherwise  specified,  should 
be  applied  before  the  machine  is  put  into  commercial  service,  and 
should  not  be  applied  when  the  insulation  resistance  is  low  owing 
to  dirt  or  moisture.  High-voltage  tests  should,  in  general,  be  made 
at  the  temperature  assumed  under  normal  operation.  High-voltage 
tests  considerably  in  excess  of  the  normal  voltages  to  determine 
whether  specifications  are  fulfilled  are  admissible  on  new  machines 
only.  Unless  otherwise  agreed  upon,  high- voltage  tests  of  a  machine 
should  be  understood  as  being  made  at  the  factory. 

[  346  ] 


TRANSFORMERS  Sec.  6 

Points  of  Application  of  Voltage.  The  test  voltage  should  be 
successively  applied  between  each  electric  circuit  and  all  other 
electric  circuits  including  conducting  material  in  the  apparatus. 

The  Frequency  of  the  alternating-current  test  voltage  is,  in 
general,  immaterial  within  commercial  ranges.  When,  however, 
the  frequency  has  an  appreciable  effect,  as  in  alternating-current 
apparatus  of  high  voltage  and  considerable  capacity,  the  rated  fre- 
quency of  the  apparatus  should  be  used. 

Table  of  Testing  Voltages.  The  following  voltages  are  recom- 
mended for  testing  all  apparatus,  lines  and  cables,  by  a  continued 
application  for  one  minute.  The  test  should  be  with  alternating 
voltage  having  a  virtual  value  (or  root  mean  square  referred  to  a 
sine  wave  of  voltage)  given  in  the  table,  and  preferably  for  tests 
of  alternating  apparatus  at  the  normal  frequency  of  the  apparatus. 

Rated  Terminal  Voltage  of  Circuit.  Rated  Output.     Testing  Voltage. 

Not  exceeding  400  volts Under  10  kw i  ,000  volts. 

Not  exceeding  400  volts 10  kw.  and  over ....  1,500  volts. 

400  and  over,  but  less  than  800  volts Under  10  kw 1,500  volts. 

400  and  over,  but  less  than  800  volts 10  kw.  and  over.  .  .  .2,000  volts. 

800  and  over,  but  less  than  1,200  volts Any 3, 500  volts. 

1,200  and  over,  but  less  than  2,500  volts Any 5,000  volts. 

2,500  and  over, Any  .  .  Double  the  normal  rated 

voltages. 

Exception. — Transformers.  Transformers  having  primary  pres- 
sures of  from  550  to  5,000  volts,  the  secondaries  of  which  are  directly 
connected  to  consumption  circuits,  should  have  a  testing  voltage 
of  10,000  volts,  to  be  applied  between  the  primary  and  secondary 
windings,  and  also  between  the  primary  winding  and  the  core. 

Special  insulation  testing  transformers  should  be  used  in  making 
insulation  tests;  the  diagrammatic  connections  of  which  are  il- 
lustrated in  Fig.  174.  However,  standard  transformers  may  be 
connected  to  give  the  desired  test  voltage.  When  standard  trans- 
formers are  used  they  should  be  well  insulated  from  the  ground 
in  order  to  protect  the  transformer  windings. 

Fig.  175  illustrates  a  method  of  connecting  six  standard  110 — 
2,200  volt  transformers  in  order  to  obtain  13,200  volts  for  testing 
purposes.  Transformers  A,  B,  and  C,  are  used  to  insulate  the 
remaining  transformers  from  the  source  of  energy,  and  if  it  is  not 
necessary  to  protect  the  circuit  they  may  be  omitted. 

When  the  scheme  of  connections  illustrated  in  Fig.  175  is  used, 
the  lead  marked  O  should  be  connected  to  ground  and  one  side  of 
the  voltmeter  should  also  be  connected  to  ground  to  prevent  any 
dangerous  difference  of  potential  from  the  voltmeter  to  the  ground. 

In  order  to  prevent  over-straining  the  insulation  of  the  trans- 
former under  test,  a  spark  gap,  in  series  with  a  resistance  should 
be  connected  across  the  test  wires.  The  spark  gap  should  be  so 
adjusted  that  accidental  over- voltage  will  discharge  across  the  gap, 
before  reaching  a  value  injurious  to  the  transformer  insulation. 

Over-voltage  may  be  caused  by  a  poor  generator  voltage  wave 
form,  or  may  be  caused,  when  a  regulating  resistance  is  used,  by  the 

[347] 


Sec.  6 


TRANSFORMERS 


distortion  of  the  supply  voltage  wave  form,  due  to  the  magnetizing 
current  of  the  testing  transformer  flowing  through  this  resistance. 

The  use  of  a  small  alternating  current  generator,  the  voltage 
of  which  can  be  varied  by  a  field  rheostat,  is  preferable  to  the  use 


of  regulating  resistance  in  a  constant  voltage  supply. 
The  spark  gap  should  be  set  in  accordance  with  Tables. 


(Art  63, 


Sec.  7.)     Should  a  discharge  occur  across  needle  gaps,  the  needle 
points  must  be  renewed,  as  a  discharge  destroys  their  calibration. 


Go. 


FIG.  175. — Insulation  test  (using  standard  transformers.) 


The  primary  voltage  may  be  found  by  multiplying  the  reading 
of  the  voltmeter  V  in  Fig.  175,  by  the  ratio  of  transformation  of 
one  transformer,  times  the  number  of  transformers  in  series  on  the 
high  potential  side. 

Let 

high  potential  voltage. 

the  reading  of  the  voltmeter  on  the  low  tension  side, 
the  ratio  of  transformation  of  one  transformer, 
the  number  of  transformers  in  series. 


E 
V 

n 

n' 

Then 

E  =  V  n  n' 


All  testing  connection  should  be  tightly  made  as  an  arc  may 
cause  undue  high  potential  strain. 

The  primary  and  secondary  leads  of  the  transformer  under  test 
should  be  connected  as  shown  in  Figs.  176  and  177. 

[348] 


TRANSFORMERS 


Sec.  6 


Insulation  test  between  primary  and  core Fig.   176. 

"    secondary    .  .  "       176. 
"       secondary  and  core "      177. 

It  is  necessary  to  make  the  above  connections,  as  portions  of  the 
windings  not  connected  to  the  testing  transformer  will  be  subjected 
to  induced  stresses  which  may  exceed  the  supply  voltage.  This 
is  caused  by  the  capacity  which  exists  between  primary  and  second- 
ary windings,  and  between  these  respective  windings  and  the  core. 

When  the  connections  have  been  made,  as  illustrated  in  Fig. 
175,  close  the  low  voltage  switch  and  slowly  adjust  the  alternator 
fields  or  the  regulating  resistance  until  the  voltage  is  increased  from 
the  lowest  obtainable  value  to  a  value  on  the  voltmeter  V,  indicating 
that  the  voltage  on  the  high  potential  side  of  the  testing  transformer 
has  reached  the  desired  maximum.  After  this  voltage  has  been 
maintained  for  the  required  time,  slowly  decrease  the  voltage  to 
the  lowest  value  possible  and  open  the  switch. 

The  frequency  should  be  maintained  at  approximately  normal 
value  during  the  test.  A  record  of  this  may  be  obtained  by  in- 


Tb  Te-sr/A/G  T&ANS. 


\H.    PI  7- 


FIG.  176. 


FIG.  177. 


serting  a  frequency  meter  in  the  circuit  or  by  determining  the  gen- 
erator speed. 

23a.  FOR  MEASURING  THE  TEST  VOLTAGE,  two  instru- 
ments are  in  common  use,  (1)  the  spark  gap  and  (2)  the  voltmeter. 

1.  The  Spark  Gap  is  ordinarily  adjusted  so  that  it  will  break  down 
with  a  certain  predetermined  voltage,  and  is  connected  in  parallel  with 
the  insulation  under  test.  It  ensures  that  the  voltage  applied  to  the 
insulation  is  not  greater  than  the  break-down  voltage  of  the  spark 
gap.  A  given  setting  of  the  spark  gap  is  a  measure  of  one  definite 
voltace,  and,  as  its  operation  depends  upon  the  maximum  value  of 
the  voltage  wave,  it  is  independent  of  wave  form  and  is  a  limit  on 
the  maximum  stress  to  which  the  insulation  is  subjected.  The 
spark  gap  is  not  conveniently  adapted  for  comparatively  low 
voltages. 

In  Spark-Gap  Measurements,  the  spark  gap  may  be  set  for  the 
required  voltage  and  the  auxiliary  apparatus  adjusted  to  give  a 
voltage  at  which  this  spark  gap  just  breaks  down.  The  spark  gap 
should  than  be  adjusted  for,  say,  10  percent  higher  voltage,  and 

[349] 


Sec.  6  TRANSFORMERS 

the  auxiliary  apparatus  again  adjusted  to  give  the  voltage  of  the 
former  break-down, which  is  to  be  the  assumed  voltage  for  the  test. 
This  voltage  is  to  be  maintained  for  the  required  interval. 

The  Spark  Points  should  consist  of  new  sewing  needles,  supported 
axially  at  the  ends  of  linear  conductors  which  are  each  at  least  twice 
the  length  of  the  gap.  There  should  be  no  extraneous  body  near 
the  gap  within  a  radius  of  twice  its  length.  Tables  of  approximate 
striking  distances  are  given  in  Sec.  7.  These  tables  should  be  used 
in  connection  with  tests  made  by  the  spark-gap  methods. 

A  Non-inductive  Resistance  of  about  one-half  ohm  per  volt  should 
be  inserted  in  series  with  each  terminal  of  the  gap  so  as  to  keep  the 
discharge  current  between  the  limits  of  one-quarter  ampere  and  two 
amperes.  The  purpose  of  the  resistance  is  to  limit  the  current  in 
order  to  prevent  the  surges  which  might  otherwise  occur  at  the  time 
of  break-down. 

2.  The  Voltmeter  gives  a  direct  reading,  and  the  different  values 
of  the  voltage  can  be  read  during  the  application  and  duration  of 
the  test.  It  is  suitable  for  all  voltages,  and  does  not  introduce 
disturbances  into  the  test  circuit. 

In  Voltmeter  Measurements,  the  voltmeter  should,  in  general, 
derive  its  voltage  from  the  high-tension  testing  circuit  either  directly 
or  through  an  auxiliary  ratio  transformer.  It  is  permissible,  however, 
to  measure  the  voltage  at  other  places, — for  example,  on  the  primary 
of  the  transformer,  provided  the  ratio  of  transformation  does  not 
materially  vary,  during  the  test;  or  that  proper  account  is  taken 
thereof. 

Spark  Gap  and  Voltmeter.  The  spark  gap  may  be  employed  as  a 
check  upon  the  voltmeter  used  in  high-tension  tests  in  order  to 
determine  the  transformation  ratio  of  the  transformer,  the  variation 
from  the  sine  wave  form  and  the  like.  It  is  also  useful  in  conjunction 
with  voltmeter  measurements  to  limit  the  stress  applied  to  the 
insulating  material. 

23b.  OVER-POTENTIAL  TEST.  For  testing  the  insulation 
between  turns,  double  potential  at  no-load  for  one  minute  is  main- 
tained. The  connections  for  such  tests  are  made  in  a  manner 
similar  to  that  for  a  core  loss  test  except  that  higher  voltages  are 
used,  depending  upon  the  rated  primary  voltage  of  the  transformer 
to  be  tested. 

When  making  over-potential  tests  the  frequency  of  the  supply 
voltage  should  be  increased  in  approximately  the  same  proportions 
as  the  voltage;  otherwise,  the  exciting  current  will  be  excessive 
and  may  be  sufficient  to  injure  the  windings  of  transformers 
having  a  small  kv-a.  rating. 

24.  HEATING  TESTS.  There  are  three  general  methods  of 
making  heat  tests  on  transformers,  two  of  which  approximate  service 
conditions,  the  other  applying  actual  full  load  to  the  transformer. 

The  first  method  consists  of  operating  the  transformer  at  full 
load  for  a  definite  length  of  time.  This  is  never  used  on  large 

[  350  ] 


TRANSFORMERS  Sec.  6 

transformers,  due  to  needless  waste  of  energy,  but  may  sometimes 
be  used  to  advantage  on  small  units. 

Fig.  188  illustrates  diagrammatically  the  connections  necessary 
when  loading  a  small  transformer.  Voltmeter,  ammeter  and  fre- 
quency meter  readings  should  be  taken  and  adjustments  made  in 
order  that  the  transformer  may  be  operated  under  normal  conditions. 

Temperatures  may  be  measured  by  thermometer  or  by  resistance, 
using  in  the  latter  case  either  the  Wheatstone  Bridge  or  the  Fall  of 
Potential  Method. 

Resistance  measurements  should  be  made  before  the  test  is  started 
and  at  different  times  during  the  test.  The  temperature  may  then 
be  calculated  from  the  increase  in  resistance  as  follows: 

Let 

t  =  the  final  temperature. 

to  =  the  initial  temperature. 

r  =  the  final  resistances. 

r0=  the  initial  resistances. 

a  =  the  temperature  coefficient  depending  on  whether  t  is  in 
degrees  C  or  F  (Section  3). 

Then  _r  (1-fq  to)-r0 

~r*r: 

For  copper  and  temperature  in  degrees  C. 
r  (1+.  00428  to)-r0 
.00428  r0 

Necessary  precaution  should  be  taken  to  obtain  the  correct 
temperature  of  the  copper  when  measuring  the  initial  resistance, 
since  a  transformer  taken  from  the  outside  into  or  transported 
from  one  room  to  another  may  have  a  decidedly  different  temperature 
than  the  room. 

The  temperature  rise  is  found  by  subtracting  to  from  t,  assuming 
that  the  transformer  was  at  room  temperature  when  the  test  began. 
If  t0  is  not  the  standard  room  temperature  (25°  C.),  then  the  room 
temperature,  instead  of  to,  is  subtracted  from  t.  If  the  room  tem- 
perature is  above  the  standard  temperature  of  25°  C.,  the 
temperature  rise  is  decreased  one-half  of  one  percent  for  each  degree 
that  the  room  temperature  is  above  25°  C.  If  the  room  temperature 
is  below  25°  C.  one-half  of  one  percent  is  added  for  each  degree 
that  the  room  temperature  is  below  25°  C. 

Temperature     Correction.     Assuming     the     room     temperature 
during  test  is  30°  C.  and  the  measured  temperature  rise  is  40°  C. 
the  actual  temperature  rise  is  found  as  follows: 
30°C.-25°C.=5°C. 


*A.  I.  E.  E.  Rules  are  in  the  process  of  revision.     Revised  rules  should  be  used 
instead  of  above. 

[351] 


Sec.  6  TRANSFORMERS 

Therefore  the  correct  temperature  rise  is 

40°C.-1°C.  =  39°  C. 

Barometric  Pressure.*  A  barometric  pressure  of  760  mm.  and 
normal  conditions  of  ventilation  should  be  considered  as  standard, 
and  the  apparatus  under  test  should  neither  be  exposed  to  draught 
nor  enclosed,  except  where  expressly  specified.  The  barometric 
pressure  needs  to  be  considered  only  when  differing  greatly  from 
760  mm. 

Barometric  Pressure  Correction.*  When  the  barometric  pressure 
differs  greatly  from  the  standard  pressure  of  760  mm.  of  mercury, 
as  at  high  altitudes,  a  correction  should  be  applied.  In  the  absence 
of  more  nearly  accurate  data,  a  correction  of  one  percent  of  the  ob- 
served rise  in  temperature  for  each  10  mm.  deviation  from  the  760 
mm.  standard  is  recommended.  For  example,  at  a  barometric 
pressure  of  680  mm.  the  observed  rise  of  temperature  is  to  be  reduced 


by 


760— 6SO 


8  percent. 


In  the  second  method  energy  equal  to  the  losses  only  is  supplied. 
It  requires  the  use  of  two  similar  transformers  connected  as  illus- 
trated in  Fig.  178.  Circuit  A  supplies  energy  equal  to  the  iron 


fierce 


FIG.    178. — Heat  test  of   two  similar  single-phase   transformers.     (Losses   only 

supplied.) 


losses  in  the  transformers.  Circuit  B  circulates  full  load  current 
through  the  windings.  It  is  general  practice  to  magnetize  the 
transformer  on  the  low  voltage  side  and  introduce  the  circulating 
current  on  the  high  voltage  side,  as  this  method  permits  the  use 
of  standard  voltages,  whereas  the  reversed  conditions  would  neces- 
sitate a  high  voltage  on  the  primary  side  with  a  very  low  voltage 
on  the  secondary  side,  resulting  in  many  complications  in  the  appa- 
ratus necessary  for  testing. 

The  voltage  required  on  circuit  A  is  that  of  the  rated  secondary 
voltage  of  the  transformer  coil. 

The  voltage  required  on  circuit  B  is  double  the  impedance  voltage 
of  one  transformer. 

[  352  ] 


TRANSFORMERS 


Sec.  6 


The  total  energy  required  in  circuit  A  is  that  equal  to  the  full 
load  iron  losses  of  both  transformers. 

The  total  energy  required  in  circuit  B  is  that  equal  to  the  full 
load  copper  losses  of  both  transformers. 

If  the  transformers  under  test  are  2,200-220  volts,  220  volts 
is  required  on  the  secondary  side  and  approximately  220  volts  is 
required  on  the  primary  side.  These  voltages  may  be  reduced  to 
110,  by  connecting  both  the  primary  and  the  secondary  windings 
of  each  transformer  in  parallel. 

If  a  three  phase  transformer  or  three  single  phase  transformers 
are  to  be  tested,  connections  may  be  made  as  illustrated  in  Fig.  179. 
This  is  exactly  similar  to  that  illustrated  in  Fig.  178  with  the  ex- 


FIG.  179.— Heat  test  of 

on  a  three-phase  circuit. 


-phase  or  one  three-phase  transformer 
(Losses  only  supplied.) 


ception  that  it  has  been  altered  so  as  to  conform  to  the  requirements 
of  three  phase  connections. 

It  will  be  noted  in  both  Figs.  178  and  179  that  the  copper  loss 
and  iron  loss  currents  are  not  equal  in  all  the  transformer  windings. 
In  Fig.  178  it  is  the  vector  sum  in  one  winding  and  the  vector  differ- 
ence in  the  other  winding,  depending  upon  the  phase  relation  of 
circuits  A  and  B.  In  Fig.  179,  it  is  the  vector  sum  or  the  vector 
difference  of  the  iron  loss  and  copper  loss  currents  depending  upon 
the  phase  relations  of  circuit  B  to  the  various  phase  voltages  of 
circuit  A.  However,  the  difference  in  heating  is  so  small  that  it  is 
negligible.  The  calculations  of  temperature  rise  may  then  be  made 
as  described  in  the  first  method. 

3rd  Method.  When  one  transformer  only  is  to  be  tested,  it  is 
possible  to  apply  full  load  current  to  the  primary  and  secondary 

12  [  353  ] 


Sec.  6 


TRANSFORMERS 


winding  without  wasting  any  energy  except  that  incident  to  the 
losses  in  the  transformer.  This  presupposes  that  circuits  of  voltages 
equal  to  the  primary  and  secondary  voltage  of  the  transformer 
are  available.  By  inserting  an  induction  regulator  in  the  primary 
or  the  secondary  circuit,  it  is  possible  to  regulate  the  transformer 
voltage  so  that  full  load  current  will  flow  through  the  transformer 
windings.  (Fig.  180.)  If  circuits  of  these  required  voltages  are 
not  available,  a  transformer  of  larger  capacity  can  be  used  (Fig.  181). 


FIG.  180. — Heat  test  of  single-phase  transformer  when  circuits  are  available  having 

the  same  voltage  as  the  primary  and  secondary  windings.      (Losses 

only  supplied.) 

If  the  primary  and  secondary  windings  of  a  transformer  are 
divided  into  two  or  more  sections,  energy  equal  to  the  full  load 
copper  losses  of  the  transformer  may  be  supplied  as  illustrated  in 
Fig.  182,  (circuits  A  and  B).  Energy  equal  to  the  iron  losses  of 
the  transformer  may  be  supplied  as  illustrated  in  Fig.  183. 


FIG.  181. — Heat  test  of  single-phase  transformer  using  induction  regulator  and 
testing  transformer.     (Losses  only  supplied.) 

r  These  two  connections  are  alternately  made  and  maintained  in 
order  to  artificially  create  heating  in  the  transformer  equal  to  that 
which  would  occur  at  full  load  under  operating  conditions.  This 
test  is  called  the  compromise  test. 

To  obtain  the  equivalent  heating  of  full  load  losses  in  a  transformer 
it  is  necessary  to  increase  the  copper  and  iron  losses  to  values  much 
higher  than  normal.  This  is  necessary  because  of  the  fact  that 

[  354  ] 


TRANSFORMERS 


Sec.  6 


their  heating  effects  are  not  superimposed  and  must  be  increased 
to  give  the  same  average  value. 

The  standard  connections  may  also  be  used  for  the  compromise 
test  (Figs.  183  and  187). 

25.  CORE  LOSS  AND  EXCITING  CURRENT  TESTS.  Con- 
nections for  the  core  loss  tests  are  illustrated  hi  Fig.  183.  This 
test  is  made  at  the  normal  operating  voltage  of  the  transformer, 
less  the  voltage  loss  due  to  the  load  current  in  the  primary.  If 


TffANS.  UND&?  TzST 


FIG.  182.  —  Connections  that  may  be  used  in  copper  loss  test,  in  connection  with 
the  compromise  heat  test. 

voltage  adjustments  are  made  by  means  of  a  variable  resistance, 
the  core  loss  of  the  transformer  may  be  as  much  as  12%  in  error, 
depending  upon  the  shape  of  the  voltage  wave  impressed  upon  the 
transformer.  It  is,  therefore,  necessary  to  use  some  means  of  cor- 
recting for  this  wave  distortion,  or  else  use  a  source  of  energy  supply 
in  which  the  voltage  is  a  pure  sinusoidal  wave.  As  tests  on  low 
voltage  line  transformers  are  usually  made  by  using  a  source  of 


TKA  NS.  UNDER  rcsr 


Fia.  183.— Iron  loss  test. 

supply  which  cannot  be  independently  controlled,  the  transformer 
is  adjusted  for  the  proper  voltage  by  means  of  a  rheostat.  When 
this  is  done  an  iron  loss  voltmeter  should  be  inserted  in  the  circuit 
as  shown  in  Fig.  183,  and  the  voltage  adjusted  until  the  iron  loss 
voltmeter  records  the  operating  voltage  of  the  transformer.  Read- 
ings of  the  wattmeter  and  ammeter  then  indicate  the  uncorrected 
value  of  the  exciting  current  and  iron  loss.  The  magnetizing  cur- 
rent may  be  calculated  by  the  method  given  in  Section  7,  Article  49. 

[  355  ] 


Sec.  6 


TRANSFORMERS 


The  frequency  should  be  maintained  at  a  constant  value  during 
this  test.  The  wattmeter  reading  should  be  corrected  for  the  power 
loss  in  the  voltmeter  and  iron  loss  voltmeter  by  subtracting  the 
losses  in  these  instruments  from  the  wattmeter  reading.  The 
losses  in  the  iron  loss  voltmeter  are  indicated  on  a  watt  scale  and 

E2 

those  of  the  voltmeter  are  -^-. 
it 

25a.  Iron  Loss  Voltmeter.  The  iron  loss  voltmeter  is  essentially 
a  wattmeter  arranged  to  read  the  iron  loss  of  a  standard  iron  circuit 
which  is  a  part  of  this  instrument.  Variations  in  wave  shape  effect 
the  iron  loss  in  the  standard  core  C.  (Fig.  184.)  If  the  wattmeter 
is  calibrated  to  read  directly  in  volts  and  an  adjustment  of  the 
supply  voltage  is  made  until  the  desired  voltage  is  read  on  this 
wattmeter  scale,  the  iron  loss  is  equivalent  to  the  iron  loss  produced 
by  a  sine  wave  of  the  same  effective  value  as  the  value  indicated 
by  the  wattmeter  scale.  This  type  of  instrument  permits  the 
testing  of  transformers  on  any  commercial  circuit,  and  the  results 


FIG.  184. — Internal  connections  of  iron,  loss  voltmeter. 


obtained  are  the  same  as  though  the  test  were  made  under  true  sine 
wave  conditions.  Fig.  184  shows  the  diagrammatic  connections 
of  an  iron  loss  voltmeter.  C  is  the  standard  laminated  core  on  which 
a  winding  W  is  placed.  Connections  from  this  winding  pass  through 
a  stationary  coil  S  to  the  terminals  P  P,  which  are  connected  to  the 
supply  voltage  mains,  as  shown  in  Fig.  183.  The  shunt  circuit 
consists  of  a  moving  coil  M  in  series  with  a  non-inductive  resistance 
R  and  the  compensating  coil  C  C  which  is  wound  parallel  to  the  series 
coil  S  and  of  an  equal  number  of  turns.  This  is  essentially  a  watt- 
meter movement  and  it  can  readily  be  seen  that  the  deflection  of 
the  wattmeter  moving  coil  M  will  be  caused  by  the  total  input  to 
the  instrument.  This  input  is  the  hysteretic  and  eddy  current  loss 
in  the  standard  iron  circuit  C  and  in  addition  the  copper  losses  in 
the  winding  W  and  the  winding  of  the  wattmeter  movement. 

Before  calibrating  the  instrument  for  a  certain  frequency  the 
adjustment  of  the  ratio  of  the  eddy  current  losses  in  the  ring,  plus 
the  shunt  copper  loss  to  the  total  loss,  is  made  by  changing  the  non- 
inductive  resistance  in  the  shunt  circuit  and  the  turns  on  the  ring. 
This  ratio  of  R  I2  loss  to  the  total  loss  is  made  to  be  about  20%  at 

[  356  ] 


TRANSFORMERS  Sec.  6 

about  two-thirds  of  the  full  scale  voltage.  After  this  adjustment 
is  made,  the  instrument  is  calibrated  in  parallel  with  an  alternating 
current  voltmeter  on  a  pure  sine  wave  voltage  of  the  required  fre- 
quency from  a  small  smooth  core  alternator.  The  scale  of  the  watt- 
meter is  drawn  to  agree  with  the  readings  of  the  alternating  current 
voltmeter.  This  wattmeter  measuring  the  iron  loss  of  the  standard 
iron  core  will  always  read  the  watts  loss  in  the  iron  core  independent 
of  wave  shape.  Therefore,  if  the  supply  voltage  is  so  adjusted 
that  correct  voltage  indications  are  given  on  the  iron  loss  volt- 
meter scale,  the  watts  consumed  by  the  standard  core  are  the  same 
as  for  a  pure  sine  wave  of  equal  value.  The  dotted  curves  in  Fig. 
185  illustrate  the  errors  for  variation  in  wave  form  when  using 
a  square  root  of  mean  square  voltmeter  to  regulate  the  voltage 
for  the  iron  loss  tests  on  transformers  with  characteristics  recorded 
in  Table  56.  The  full  line  curves  represent  the  error  when  using  an 
iron  loss  voltmeter.  With  a  variation  of  10%  in  frequency  there 
will  not  be  an  error  in  loss  greater  then  l/^%. 

Core  losses  should  always  be  measured  on  the  low  tension  side 
of  the  transformer  to  avoid  using  a  high  potential  test  circuit. 


TABLE  56 

Curve 

Transformer  with 

Tested  with 

A 

B 
C 
D 

E 
F 

14%  eddy  loss 
20%  eddy  loss 
30%  eddy  loss 
14%  eddy  loss 
20%  eddy  loss 
30%  eddy  loss 

R.  m.  s.  voltmeter 
R.  m.  s.  voltmeter 
R.  m.  s.  voltmeter 
Iron  loss  voltmeter 
Iron  loss  voltmeter 
Iron  loss  voltmeter 

26.  RESISTANCE  MEASUREMENTS.  The  resistance  of  a 
circuit  varies  with  temperature,  and  for  comparative  purposes  all 
values  for  resistance  are  corrected  in  order  to  indicate  the  true 
resistance  at  a  temperature  of  25°  C.  Methojds  of  correcting  for 
temperature  are  illustrated  in  Section  3,  Art.  19. 

The  resistance  of  the  coils  of  a  transformer  may  be  determined 
by  the  use  of  a  Wheatstone  Bridge,  or  by  The  Fall  of  Potential 
Method. 

When  resistance  values  are  determined  by  the  Wheatstone  Bridge 
no  corrections  other  than  for  temperature  are  necessary.  This 
method  is  seldom  used  for  measuring  resistance  values  of  less  than 
one  or  two  ohms. 

The  Fall  of  Potential  Method,  as  commonly  used,  necessitates 
the  use  of  direct  current,  as  the  inductive  effect  of- alternating  current 
will  prevent  the  determination  of  accurate  results. 

Fig.  186  illustrates  diagrammatically  the  circuit  arrangement 
necessary  when  determining  resistance  by  The  Fall  of  Potential 

[  357  ] 


Sec.  6 


TRANSFORMERS 


Method.  The  illustration  applies  to  the  measurement  of  the  re- 
sistance of  the  secondary  coils,  but  is  equally  applicable  to  the 
measurement  of  the  resistance  of  the  primary  coils. 

When  measuring  resistance  by  the  fall  of  potential  method,  the 
voltmeter  pointer  may  show  a  continued  tendency  to  vibrate,  due  to 
the  changing  magnetic  field  (building  up)  in  the  transformer  core. 
To  eliminate  this,  the  opposite  winding  should  be  short  circuited. 
Remove  the  short  circuit  before  changing  value  of  current  for  a 
second  or  third  reading. 

Corrections  must  be  made  for  the  current  flowing  through  the 
voltmeter,  which  value  varies  in  accordance  with  its  resistance. 


FIG.  185.  —  Error  in  measured  iron  loss  with  variation  in  form-factor  of  voltage 

wave. 

The  following  formula  will  give  the  correct  value  for  the  resistance 
of  the  coil,  under  test. 
Let 

R  =the  resistance  of  transformer  coil  under  test. 

R'  =the  resistance  of  the  voltmeter. 

E  =the  voltmeter  reading. 

I    =  the  ammeter  reading. 

Iv  =  the  current  flowing  through  the  voltmeter. 

Ic  =the  corrected  current  or  the  actual  current  flowing  through 
the  coil  under  test. 

E 


Ic  =I-I 


[358] 


TRANSFORMERS 

Therefore  the  resistance  of  the  coil  under  test  is 
E 


Sec.  6 


When  measuring  the  resistance  of  a  large  transformer  the  ratio  of  Iv 
to  I  is  negligible. 

With  the  resistance  of  both  primary  and  secondary  windings 
known,  it  is  possible  to  calculate  the  copper  loss  I2  R  of  the  trans- 
former in  each  winding;  and  the  sum  of  these  should  correspond  very 


fuse 


Trsr 


FIG.  186.  —  Measurement  of  resistance  by  the  fall  of  potential  method. 

closely  to  the  copper  loss  of  the  transformer  as  measured  by  a  watt- 
meter. 

When  making  tests  in  accordance  with  the  connections  shown  in 
Fig.  186,  the  following  procedure  should  be  applied: 

Close  the  switch  and  regulate  the  controlling  resistance  until  full 
load  current  is  obtained. 

Read  the  voltmeter  and  ammeter. 

Increase  the  resistance  until  a  lower  value  of  current  is  obtained, 
then  also  read  the  instruments. 


TKAMS.  UNDER  7&r 


000 
OOO 
OOO 
OOO 
000 
000 


Fuse 


oe  VARIABLE  RCS/STANCE 
FIG.  187. — Copper  loss  or  impedance  test. 


Take  several  readings  on  each  coil  at  different  current  values. 

Disconnect  voltmeter  before  opening  circuit. 

Reduce  the  current  to  a  minimum  before  opening  the  switch. 
The  current  should  flow  through  the  transformer  windings  for  as 
short  a  time  as  is  possible,  as  the  heating  produced  will  appreciably 
affect  the  values  of  the  resistance  obtained. 

27.  COPPER  LOSS  TEST.  It  is  usual  to  measure  the  impedance 
drop  and  the  copper  loss  of  a  transformer  on  the  high  voltage  side, 
for  on  the  high  voltage  side  more  accurate  voltage  readings  can  be 

[359] 


Sec.  6  TRANSFORMERS 

obtained.  The  connections  for  a  copper  loss  test  are  illustrated 
in  Fig.  187  and  indicate  all  the  meters  that  are  required.  If  extreme 
accuracy  is  desired,  the  wattmeter  and  the  ammeter  readings  must 
be  corrected  for  the  current  taken  by  the  voltmeter  and  the  watt- 
meter potential  winding.  The  wattmeter  reading  may  be  corrected 
by  subtracting  the  energy  absorbed  by  the  potential  coils  of  the 
wattmeter  and  voltmeter.  The  value  of  the  absorbed  energy  may 
be  obtained  by  multiplying  the  square  of  the  voltage  indicated  by 
the  sum  of  the  reciprocals  of  the  resistance  of  the  voltmeter  and 
voltage  coils  of  the  wattmeter.  The  result  subtracted  from  the  watt- 
meter reading  will  give  the  input  to  the  transformer  in  watts.  The 
ammeter  indicates  not  only  the  current  in  the  transformer  but  also 
the  current  flowing  through  the  potential  coil  of  the  wattmeter  and 
voltmeter.  Therefore,  the  amount  of  current  indicated  is  slightly 
greater  than  that  actually  flowing  through  the  transformer  coils. 
However,  this  is  practically  negligible.  The  corrected  wattmeter 
readings,  taken  when  the  voltage  has  been  adjusted  so  that  full  load 
current  flows  through  the  ammeter,  will  give  the  sum  of  the  full  load 
copper  losses  in  the  primary  and  secondary  coils  of  transformer. 

During  the  test,  the  frequency  should  be  maintained  at  a  constant 
value. 

28.  REACTANCE  DROP.     The  reactance  drop  of  a  transformer 
may  be  calculated  in  accordance  with  the  formulae  following : 
Let 

E     =  the  voltmeter  reading,  Fig.  187. 

I      =the  ammeter  reading,  Fig.  187. 

We  =the  corrected  wattmeter  reading,  Fig.  187. 

X      =the  total  reactance  of  the  transformer  windings  referred 

to  the  primary,  in  ohms. 
z      =the  total  impedance  of  the  transformer  windings  referred 

to  the  primary,  in  ohms. 
rp     =the  resistance  of  the  primary  winding  of  the  transformer, 

in  ohms. 
rs     =  the  resistance  of  the  secondary  winding  of  the  transformer, 

in  ohms, 
rt     =the  total  resistance  of  the  transformer  windings  referred 

to  the  primary,  in  ohms, 
n      =the  ratio  of  transformation, 
f      =the  frequency  in  cycles  per  second. 
The  reactance  may  be  found  by  two  methods: 

Tfi 

1st.     z      =  -y-  from  copper  loss  test. 

rtl   =  — p  from  copper  loss  test. 

We 
rt    = 


A/E2-rt2  P        /- 

— —       =vz2-rt2 

[  360  ] 


TRANSFORMERS  Sec.  6 

E 
2nd.  z      —~T~  fr°m  copper  loss  test. 

rt     =rp+n2rs  from  resistance  test. 

A/E2-rt2I2        . 

"      - 


—  "V  2 it 

The  various  values  necessary  in  this  calculation  are  obtainable 
in  accordance  with  the  methods  described  herein. 

In  both  formulae  given,  the  inductance  of  the  transformer  coils 
referred  to  the  primary  may  be  found  as  follows : 


2xf 


henries 


From  the  values  of  resistance  and  reactance  thus  obtained,  the 
regulation  of  the  transformer  for  any  power  factor  may  be  obtained. 
(Section  7,  Article  49.) 

29.  REGULATION.  The  regulation  of  a  transformer  may  be 
obtained  by  calculation  as  given  in  Sec.  7,  Article  49,  or  on  small 
transformers  it  is  possible  to  measure  the  regulation  directly  by  con- 
necting the  transformer  to  a  constant  voltage  source,  Fig.  188,  and 

fuse 


First: 


Fio.  188. — Connections  for  regulation  test. 

loading  it  to  its  full  capacity  with  a  lamp  bank  or  other  non-induc- 
tive resistance.  The  secondary  voltage  of  the  transformer  at  full 
load  and  at  no  load  is  then  determined,  and  the  ^difference  between 
these  values  divided  by  the  secondary  voltage  at  full  load,  multi- 
plied by  100,  gives  the  regulation  in  percent. 

The  regulation  of  a  transformer  on  a  non-inductive  load  is  about 
2%;  therefore,  this  method  of  obtaining  regulation  is  not  very  accu- 
rate, as  an  error  in  the  voltage  readings  of  1%  will  result  in  an  error 
of  approximately  50%  in  the  measured  regulation.  Much  more 
accurate  results  may  be  obtained  by  calculation. 

30.  RATIO.  In  order  to  guard  against  possible  mistakes  in  coil 
winding  and  assembling,  a  test  should  be  made  to  accurately  de- 
termine the  ratio  of  the  primary  to  the  secondary  voltage.  This 
may  be  done  by  connecting  the  transformer  under  test  to  a  trans- 
former of  known  ratio  as  illustrated  in  Fig.  189.  The  readings  of 
the  voltmeter  will  give  the  ratio  of  the  transformer  under  test. 

[361] 


Sec.  6 


TRANSFORMERS 


Any  convenient  voltage  readings  large  enough  to  obtain  the  desired 
accuracy  may  be  used. 

Let 


n0 
E' 


'the  secondary  voltage  of  the  standard  transformer. 
=  the  ratio  of  the  standard  transformer, 
'the  secondary  voltage  of  the  transformer  under  test, 
n'    =the  ratio  of  the  transformer  under  test. 
Then 

.         no  Jiio 

n'    = 


E' 

31.  POLARITY.  The  phase  relation  between  the  transformer  pri- 
mary and  secondary  terminal  electromotive  forces  is  termed  the 
polarity  of  the  transformer. 


FIG.  189. — Connections  for  ratio  test. 

When  the  windings  of  a  transformer  are  so  connected  that  the  in- 
stantaneous flow  of  current  is  into  terminal  A  and  out  of  terminal  C, 
then  if  A  is  considered  positive,  C,  Fig.  190,  is  also  positive. 


FIG.  190. 

(A)  The  polarity  of  a   transformer   may  be  determined   when 
determining  the  ratio  by  connecting  the  transformers    under  test 
as  illustrated  in  Fig.  189.    If  the  polarity  is  the  same  as  that  of  the 
standard  transformer  the  lamps  will  both  be  bright.     If  it  is  the 
opposite,  the  lamps  will  both  be  dark. 

(B)  The  polarity  of  a  transformer  may  also  be  determined  by 
connecting  a  direct  current  source  of  energy  to  the  low  tension  wind- 

[  362  ] 


TRANSFORMERS 


Sec.  6 


ing,  breaking  this  connection  and  noting  the  deflection  of  a  direct 
current  voltmeter  connected  to  the  high  tension  winding.  If  the 
deflection  on  the  voltmeter  scale  is  positive,  the  lead  of  the  trans- 
former connected  to  the  positive  terminal  of  the  voltmeter  is  a 
positive  lead,  and  the  terminal  of  the  low  voltage  side  connected  to 
the  negative  wire  of  the  direct  current  supply  is  also  positive. 

(C)  Polarity  may  be  determined  by  the  method  shown  in  Fig.  191. 
If  220/volts  a-c.  is  supplied  to  the  high  voltage  winding  of  a  trans- 
former with  a  ratio  of  10  to  1,  the  voltage  of  the  low  voltage  winding 
is  22.  If  B  and  D  are  connected,  a  voltmeter  connected  to  A  and 
C  will,  when  the  transformer  is  of  positive  polarity,  read  the  difference 
between  the  impressed  voltage  and  the  induced  voltage,  or  220  —  22  = 
198  volts.  If,  however,  the  transformer  polarity  is  negative,  then 
the  voltmeter  connected  to  A  and  C  will  read  the  sum  of  the  impressed 
and  induced  voltages,  or  242  volts. 

Polyphase  transformers  may  be  tested  for  polarity  in  a  manner 
similar  to  that  for  single  phase  transformers;  more  satisfactory 


f>   5 
Fia.  191. — Connections  for  polarity  test. 


results  are  obtained  by  testing  each  phase  of  the  transformer  sepa- 
rately. 

TRANSFORMER  SPECIFICATIONS 

32.  Transformers.     In   purchasing   transformers  definite  values 
for  the  following  data  should  be  obtained : 

1.  Kv-a.  capacity  of  transformer. 

2.  Power  factor  of  load. 

3.  Primary  voltage  of  transformer. 

4.  Secondary  voltage  of  transformer. 

5.  Frequency  of  system. 

6.  Single  phase  or  polyphase  transformers. 

7.  Efficiency  at  %,  Yi,  %,  full  and  1^  full  load. 

8.  Regulation  at  full  load  and  power-factor  given  in  item  2. 

9.  Core  loss. 

10.  Exciting  current. 

33.  Transformer  Oil.     As  there  is  some   variation  in   manufac- 
turers' oil  specifications,  two  different  specifications  are  given. 

The  first  specification  was  obtained  from  the  Westinghouse  Elec- 

[  363  ] 


Sec.  6 


TRANSFORMERS 


trie  &  Manufacturing  Company,  and  the  specification  contained 
in  Table  57  from  the  General  Electric  Company. 

Transformer  Oil  Specification. 

Quality:  The  oil  must  be  a  pure  mineral  oil  obtained  by  frac- 
tional distillation  of  petroleum,  unmixed  with  any  other  substances. 
It  must  not  contain  moisture,  acid,  alkali,  or  sulphur  compounds. 


FIG.  192. — Distribution  of  electrostatic  field  for  different  shaped  terminals. 


Flash  and  Fire:  The  flash  point  of  the  oil  must  not  be  less  than 
171°  C.  (340°  F.)  and  the  fire  point  must  not  be  less  than  198°  C. 
(390°  F.). 

Evaporation:    The  oil  must  not  show  a  loss  by  evaporation  of 


/          2          3          4          S          6          7 

D/STANCC  //V  /NCHCS 

FIG.  193. — Disruptive  value  of  dry  oil  for  different  shaped  terminals. 


more  than  twenty-five  hundred ths  of  one  percent  (0.25%),  after 
heating  for  eight  hours  at  a  temperature  of  100°  C. 

Insulation:  The  oil  must  show  an  average  breakdown  test  of  not 
less  than  35,000  volts  on  a  0.15"  gap. 

Color:  It  is  desirable  that  the  color  of  the  oil  be  as  light  as  possible. 

[  364  ] 


TRANSFORMERS 


Sec.  6 


Viscosity :  It  is  desirable  that  the  oil  be  as  fluid  as  possible,  low 
viscosity  being  a  point  in  its  favor. 

Deposit:  The  oil  must  not  show  a  deposit  or  any  change  other 
than  a  darkening  of  color,  after  being  raised  to  a  temperature  of 
232°  C.  (450°  F.)  by  heating  gradually  and  uniformly  for  one  hour 
and  then  allowing  it  to  stand  at  room  temperature  for  twelve  hours. 


The  break-down  voltage  of  oil  is  affected  by  the  shape  of  the  testing 
terminals.  The  electrostatic  field  between  discs,  spheres  and  needle 
points  is  illustrated  in  Fig.  192.  The  disruptive  voltage  of  dry  oil 
measured  between  variously  shaped  terminals  is  given  in  Fig.  193. 
There  are  two  standard  methods  for  testing  the  dielectric  strength 
of  oil. 

1st.  method.  This  method  consists  of  testing  terminals  made  of 
y£  brass  balls  fastened  to  Ty  rods.  These  terminals  are  placed 
vertically  in  a  glass  tube  and  so  arranged  that  they  may  be  adjusted 
for  different  distances,  0.15''  usually  being  considered  standard. 
With  this  gap  spacing  average  dry  oil  should  not  break  down  at  less 
than  35,000  volts  with  a  sine  wave  e.m.f. 

2nd.  method.  This  method  consists  of  two  half-inch  brass  discs, 
mounted  on  %"  rods  and  arranged  horizontally  in  a  receptacle  hold- 
ing oil.  The  discs  may  be  adjusted  for  different  distances,  although 
0.2"  has  been  adopted  as  standard.  With  this  gap  spacing  dry  oil 
should  not  break  down  at  less  than  30,000  volts,  with  a  sine 
wave  e.m.f. 

Table  57  gives  the  characteristics  of  two  oils  furnished  by  the 
General  Electric  Company.  The  No.  8  oil  is  used  for  water-cooled 
and  oil-cooled  transformers  and  is  designed  for  a  normal  temperature 
rise  not  to  exceed  40°  C.  The  No.  12  oil  is  for  oil-cooled  apparatus 
when  the  operating  temperature  rise  is  about  40°  C.  The  dielectric 
strength  of  these  oils  is  30,000  volts  when  the  test  is  applied  between 
two  }/%  discs  set  0.2"  apart. 


TABLE  57 
TRANSFORMER  OIL 

.    No.  8  Oil 

No.  12  Oil 

Flashing  Temperature  

130°  C. 
145°  C. 
-15°  C. 
0.830 
40 

160°  C. 
175°  C. 
-10°  C. 
0.850 
60 

Burning  Temperature    

Freezing  Temperature  
Specific  Gravity  (15.5°  C.)  
Viscosity  (,40°  C  ) 

33a  Moisture  in  Oil.  Moisture  in  oil  may  be  detected  by 
testing  samples  obtained  from  the  bottom  of  the  transformer  case. 
If  water  is  present  in  large  quantities  it  will  be  apparent  to  the  eye. 

[  365  ] 


Sec.  6 


TRANSFORMERS 


If  present  in  small  quantities  it  may  be  detected  by  inserting  in  the 
oil  an  iron  wire  heated  to  a  temperature  slightly  below  a  dull  red; 
a  very  decided  hissing  or  crackling  sound  will  indicate  the  presence 
of  moisture.  If  moisture  is  present  copper  sulphate  crystals  finely 
pulverized  and  placed  on  a  watch  crystal  will  turn  a  very  deep  blue 
when  covered  with  the  oil  under  test.  The  best  test,  however,  is  a 
test  of  dielectric  strength  by  the  spark  gap  methods  mentioned  above. 
Fig.  194  shows  the  effect  of  various  percentage  of  water  in  medium 
and  Fig.  195  in  light  oil. 


30\ 


20 


.OS     JO      ./S      .20     .ZS     .30 


FIG.  194.  —  Influence  of  moisture  on  the  dielectric  strength  of  oil  of  medium  viscosity. 


34.  THE  OPERATION  OF  LARGE  vs.  SMALL  TRANSFORM- 
ERS. The  capacity  of  transformers  for  pole  line  used  is  limited,  not 
only  because  of  the  mechanical  problem  of  properly  supporting  them, 
but  also  because  of  the  limited  distance  to  which  low  tension  current 
can  be  economically  transmitted. 

Large  installations  of  light  or  power  usually  require  individual 
transformers,  but  when  it  is  possible  to  select  a  load  center  from 
which  a  number  of  relatively  small  consumers  can  be  economically 
reached,  a  considerable  saving  in  investment  and  in  energy  loss  can 
be  effected.  Relatively  small  transformers  connected  to  a  number 
of  small  individual  loads  usually  require  a  transformer  capacity  of 
approximately  80%  of  the  connected  load.  Relatively  large  trans- 
formers connected  to  a  number  of  small  consumers  usually  require  a 
transformer  capacity  of  from  30%  to  50%  of  the  connected  load. 

[366] 


TRANSFORMERS 


Sec.  6 


This  reduction  in  transformer  capacity  necessary  per  kw.  connected 
load  is  due  to  the  diversity  factor  of  the  individual  loads  connected, 
and  in  a  distributing  system  is  one  of  the  most  important  problems 
encountered. 


.05     JO      .IS     .20     .25    .30 


FIG.  195.  —  Influence  of  moisture  on  dielectric  strength  of  light  oil. 

It  is  self-evident  that  the  grouping  of  loads  on  a  single  transformer 
can  be  overdone,  in  that,  when  the  secondary  distribution  is  ex- 
tended for  great  distances  from  the  transformer,  the  cost  of  copper 
will  more  than  offset  the  transformer  economies.  Therefore,  this 
problem  must  be  studied  locally,  giving  due  consideration  to  the 
character  of  the  individual  loads,  their  distance  apart  and  the  saving 
in  transformer  investment  and  in  transformer  efficiency  that  may  be 
effected  as  illustrated  by  the  following. 

A  relatively  large  transformer  is  superior  to  a  number  of  relatively 
small  transformers  having  the  same  total  capacity,  since 

The  cost  per  kv-a  is  less; 

The  core  loss  per  kv-a  is  less; 

The  copper  loss  per  kv-a  is  less. 

Increased  economy  in  distribution  may  be  effected  by  the  parallel 
operation  of  transformers  connected  to  a  net  work  as  illustrated  in 
Article  8,  Section  7. 

35.  A  POLYPHASE  TRANSFORMER  is  a  single  unit  designed 
to  transform  polyphase  energy  to  polyphase  energy. 

Polyphase  transformers  are  lighter  in  weight  and   cost  less  per 

[3671 


Sec.  6 


TRANSFORMERS 


kv-a  than  single-phase  transformers  of  equal  total  capacity,  but  the 
failure  of  one  section  of  a  polyphase  transformer  necessitates  re- 
moving it  from  the  line.  If  single-phase  units  are  used,  one  trans- 
former can  be  readily  replaced  in  case  of  damage.  Therefore,  when 
polyphase  transformers  are  used,  it  is  necessary  to  carry  a  more 
expensive  reserve  stock  than  would  be  necessary  if  single-phase 
transformers  are  used.  These  factors  usually  decide  in  favor  of 
single-phase  transformers. 

36.  PARALLEL  CONNECTING  OF  TRANSFORMERS.  When 
connecting  transformers  for  parallel  operation  it  is  generally  ad- 
visable to  test  the  polarity  of  the  various  transformers  before  per- 
manent connections  are  made.  This  may  be  done  by  connecting 
the  primary  leads  of  all  the  transformers  to  the  primary  circuit. 

The  secondary  leads  of  one  of  the  transformers  are  then  con- 
nected to  the  secondary  mains,  establishing  secondary  voltage  or 
voltages  to  which  the  secondary  voltages  of  the  other  transformers 
must  conform.  This  is  determined  as  follows: 

Connect  one  lead  of  each  of  the  remaining  transformers  to  one  of 
the  secondary  mains.  The  remaining  transformer  secondary  leads 
may  be  connected  to  the  other  secondary  mains,  provided  voltage 
does  not  exist  between  the  lead  and  the  main  to  which  it  is  to  be 
connected.  This  condition  may  be  determined  by  either  a  voltmeter 
or  a  lamp. 

When  the  polarity  of  single-phase  and  two-phase  transformers  is 
known,  the  connections  can  be  readily  determined.  The  phase 
relation  of  three-phase  transformers  or  of  single-phase  transformers 
connected  to  a  three-phase  system  is  complicated  and  therefore 
vector  diagrams  are  given  in  order  to  show  the  phase  relation  existing 
in  the  more  important  connections. 

In  the  following  illustrations  each  transformer  lead  is  identified 
by  a  number  which  is  placed  on  the  vector  diagram  to  indicate  the 
transformer  lead  which  that  particular  end  of  the  vector  represents; 
thus,  in  Fig.  196  the  vertical  line  on  the  left  hand  side  illustrates  the 


FIG.  196. 


primary  winding.  If  the  polarity  of  the  corresponding  secondary 
winding  is  positive,  the  numbers  indicating  the  respective  ends  of 
the  vector  for  the  same  phase  relation  will  be  identical.  If  the 
polarity,  however,  is  the  reverse  or  negative,  then  the  numbers  on 
the  ends  of  the  vectors  are  reversed,  indicating  that  the  phase  relation 

[  368  ] 


TRANSFORMERS 

A 


Sec.  6 


_  f  %  PR/ MARY  VECTORS 

/WvwJf     JVwwvU    JWwv/vAS        4^3 

/AA/V   3/Wy  J-AA^6         6A/  " 

«7     I  I     b      \  \     C 

£/     \a          TRANSFORMER 

SECONDARY  VECTORS 
3 


A'  B' 


SECONDARY  MAIN 
VECTORS 


Fio.  197.— Transformers  connected  "A"  primary  and  "A"  secondary. 

A 


VECTORS 


7RANSrO*f1E# 
2    .  PR/MARY  VECTORS 


SECONDARY  VECTORS 


SECONDARY 

MAIN  VECTORS 


FIG.  198. — Transformers  connected  "Y"  primary  and  "A"  secondary. 
[369] 


Sec.  6  TRANSFORMERS 

of  the  corresponding  secondary  leads  is  opposite  that  of  the  primary 
leads. 

The  voltage  between  the  supply  mains  is  used  as  a  basis  of  refer- 
ence, as  this  voltage  is  independent  of  the  method  used  in  connecting 
the  apparatus  to  the  source  of  energy.  Therefore,  in  Fig.  197  the 
voltages  between  A,  B  and  C  are  "  A  "  voltages.  All  vectors  are 
assumed  to  rotate  in  a  counter-clock-wise  direction.  Lead  1  of 
transformer  a  is  connected  to  supply  main  A.  Lead  2  of  trans- 
former a  is  connected  to  supply  main  B.  Therefore  the  phase  rela- 
tion of  transformer  a  is  the  same  as  that  of  the  voltage  between 
supply  mains  A  and  B.  In  a  like  manner  transformers  b  and^c  have 
the  same  phase  relation  respectively  as  the  voltages  between  supply 
mains  B  — C  and  A  — C.  These  transformers  are  assumed  to  have 
positive  polarity.  Therefore,  the  voltage  vectors  between  the 
secondary  leads  of  the  transformers  will  be  in  phase  with  their 
respective  primary  voltages  and  the  phase  relation  of  the  voltages 
between  secondary  mains  A',  B'  and  C'  will  be  the  same  as  between 
supply  mains  A,  B  and  C.  This  method  of  connection  is  known  as 
the  delta  delta  connection.  If  the  ratio  of  transformation  is  one 
to  one,  A  may  be  connected  to  A',  B  to  B'  and  C  to  C'. 

The  connections  in  Fig.  201  are  similar  to  those  in  Fig.  197,  but 
negative  transformer  polarity  has  been  assumed.  Therefore,  as  the 
voltages  are  180°  out  of  phase,  it  is  impossible  to  parallel  these  trans- 
former banks  with  symmetrical  connections.  By  comparing  the 
secondary  vectors  of  Figs.  197  and  201,  it  will  be  noted  that,  al- 
though the  vector  representing  the  voltage  of  transformer  a,  Fig.  197, 
bears  the  same  angular  relation  to  that  representing  the  voltage  of 
the  transformer  a,  Fig.  201,  it  is  reversed  and  the  delta  voltages  are 
reversed. 

If  the  secondary  leads  of  each  one  of  these  transformers  be  re- 
versed, the  vector  relation  of  the  secondary  voltage  becomes  the 
same  as  that  shown  in  Fig.  197  (compare  Fig.  202).  The  crossed 
leads  thus  compensate  for  the  negative  polarity  and  make  it  possible 
to  connect  this  bank  in  parallel  with  that  shown  in  Fig.  197. 

Transformers  may  be  connected  with  the  primary  in  Y  and  the 
secondary  in  A  as  shown  in  Figs.  198  and  203.  In  Fig.  198,  which 
is  for  positive  polarity,  No.  1  lead  of  transformer  a  is  connected  to 
the  supply  main  A,  No.  3  lead  of  transformer  b  is  connected  to  the 
supply  main  B,  No.  5  lead  of  transformer  c  is  connected  to  the  supply 
main  C.  Leads  2,  4  and  6  are  connected  together.  Therefore, 
their  vector  relations  are  as  illustrated  for  the  transformer  primary 
vectors.  The  voltage  in  each  transformer  secondary  coil  is  in  phase 
with  the  primary  voltage  and  since  lead  No.  2  is  connected  to  lead 
No.  3,  lead  No.  4  to  No.  5  and  lead  No.  6  to  No.  1,  the  voltages  of 
the  transformer  secondary  will  be  as  illustrated  in  the  diagram. 
Therefore,  the  voltages  between  A',  B'  and  C'  are  in  phase  with  the 
secondary  voltages,  but  at  an  angle  of  30°  from  the  primary  voltage. 

In  Fig.  203,  the  secondary  phase  voltages  are  180°  in  phase  relation 
from  those  in  the  primary.  Therefore,  the  delta  voltage  between 
the  secondary  leads  of  the  transformer  and  between  the  secondary 

[370] 


TRANSFORMERS 

A 


Sec.  6 


A  B 


SUPPLY  MAIN 
vccroKs 


B 


i         i ,       w 

\  a  J_^    J_^        /v 

/vwwvk    3www4    J^wws/^    j^_ \? 

xp?  j^  jryy  ' 


C'        * 

/I 


o' 


C' 


Fia.  199. — Transformers  connected  "A"  primary  and  "Y"  secondary. 

A 


A  3\  SECONDARY  VCCTOeS 


FIG.  200. — Transformers  connected  "A"  primary  and  "Y"  secondary. 
[  371  ] 


Sec.  6 


TRANSFORMERS 

A 


/Vwwvtf     jUww^    ^U/\AA/J£     S. 


VECTORS 


7/PANSrORMEX 


'P^vw 


3     6      4 


A'  B1  C' 


«\       /c 

.  A 

B' .<? 


VECTORS 


A' 


Fia.  201.— Transformers  connected  "A"  primary  and  "A"  secondary. 


A3 


SUPPLY  MAIM 


A/WVV?     ^UwvJ^      J-U\AMJ6       Si 


A 

c/   V 


TRANSFORMER 


/AAA^   ^AAA^    ^AAA6 

a     \          \     b  I     c  S, 


6      3 


^     , 


,      x 
c  7 


JCCONOARr  vccroes 


3     **< 


A'  B'  C' 


FIG.  202.— Transformers  connected  "A"  primary  and  "A"  secondary. 
[  372  ] 


TRANSFORMERS 

A 


Sec.  6 


<5uPPLY  MAIN 


^UwvA/k    J"UwvJ6      -ts£* 


TRANSFORMER 
SECONDARY  VECTORS 


SECONDARY  MA/N 

rccro/ts 


FIG.  203. — Transformers  connected  "Y"  primary  and  "A*   secondary. 

A 
NKATIVC  PoLAtirr  SUPPLY  MAW 


TRANSFORMER 


SCCONDARf  VECTORS 


FIG.  204. — Transformers  connected  "Y"  primary  and  "A"  secondary. 
[373] 


Sec.  6  TRANSFORMERS 

mains  is  the  reverse  of  that  in  Fig.  198.  By  reversing  the  primary 
leads  as  illustrated  in  Fig.  204,  the  voltage  impressed  upon  the  pri- 
mary and,  in  consequence,  the  voltage  induced  in  the  secondary  is 
reversed.  Therefore,  even  though  the  transformers  have  opposite 
polarity  they  may  be  connected  in  parallel. 

Transformers  of  opposite  polarity,  connected  A  primary  and 
Y  secondary  are  shown  in  Figs.  199  and  205.  Such  transformers 
cannot  be  connected  in  parallel.  However,  by  reversing  the 
connections  as  shown  in  Fig.  200,  they  may  be  connected  in 
parallel. 

Transformers  as  illustrated  will  parallel  as  follows:  Fig.  197  with 
202,  198  with  204,  199  with  206,  200  with  205  with  symmetrical 
connections. 

Transformers  as  illustrated  in  Figs.  198  and  204  may  be  con- 
nected to  those  illustrated  in  Figs.  200  and  205  provided  A'  Fig.|198 
is  connected  with  C'  Fig.  200;  B'  Fig.  198  with  A'  Fig.  200;  C'  Fig. 
98  with  B'  Fig.  200. 

Transformers  as  illustrated  in  Figs.  199  and  206  may  be  connected 
in  parallel  to  transformers  as  illustrated  in  Fig.  203,  provided  A', 
Fig.  199,  is  connected  to  B'  Fig.  203;  B'  Fig.  199  to  C'  Fig.  203;  C' 
Fig.  199  to  A'  Fig.  203. 

Transformers  as  illustrated  in  Fig.  201  cannot  be  connected  in 
parallel  with  any  of  the  other  transformer  connections  illustrated. 

In  order  that  transformers  should  operate  successfully  when  con- 
nected in  parallel  or  when  connected  to  a  three-phase  source  of  supply 
it  is  necessary  that  a  proper  phase  relation  be  maintained  and  also 
that  the  transformers  thus  connected  shall  have  the  same  reactance 
and  resistance.  This  is  strictly  true.  Within  commercial  limits, 
however,  the  division  of  load  is  correct  if  the  voltage  ratio  and  the 
impedance  are  the  same,  even  though  the  resistance  components  may 
differ.  If  this  condition  is  not  maintained,  the  transformers  will 
not  share  the  load  equally  and  the  three-phase  secondary  voltages 
will  be  distorted. 

The  method  of  connecting  two  transformers  to  a  three- phase  four- 
wire  system,  as  illustrated  in  Fig.  207,  provides  a  balanced  three- 
phase  secondary  supply,  but  produces  an  unbalanced  condition  on 
the  primary  system  for  which  reason  it  is  seldom  used. 

Fig.  208  illustrates  the  incorrect  method  of  connecting  transform- 
ers as  above  described.  This  method  produces  a  distorted  secondary 
voltage  as  well  as  unbalancing  the  primary  system. 

The  method  of  transforming  three  to  two  phase  is  illustrated  in 
Figs.  209  and  210.  Lead  1  of  transformer  a  is  connected  to  the 
supply  main,  A ;  lead  2  (it  should  be  noted  that  this  lead  2  is  not  the 
end  of  the  winding,  but  is  a  tap  at  the  86.6%  point)  of  the  trans- 
former a  is  connected  to  the  junction  of  coils  b  and  c  of  the  second 
transformer.  Transformer  lead  3  is  connected  to  the  supply  B. 
Transformer  lead  4  is  connected  to  the  supply  main  C.  The  voltages 
impressed  on  the  transformer  windings  are  illustrated  vectorially 
in  Fig.  209.  As  the  polarity  has  been  assumed  to  be  positive,  the 
secondary  vectors  bear  the  same  phase  relations  as  those  in  the  pri- 

[  374  ] 


TRANSFORMERS 

A 

NEGATIVE  POLARITY 

B  C 


Sec.  6 


SUPPLY  MAIN 
VECTORS 


TRANSFORMER 
PRIMARY  VECTORS' 


4     b 


66L~  TRANSFORMER 

3CCONOAKY  VECTORS 


C' 


FIG.  205. — Transformers  connected  "A"  primary  and  "Y"  secondary. 

A 

r/Y£  POLARITY 

SUPPLY  MAIN 

VECTORS 


4  SECONDARY  VECTORS 

*/* 

A' 


B' 


SECONDARY  MAIN 
VECTORS 


FIG.  206. — Transformers  connected  "A"  primary  and  "Y"  secondary. 
['375  ] 


Sec.  6 


TRANSFORMERS 


flosmve  FbLAe/rr 


SUPPLY  MA/N 
vecroes 


4*N? 

y^c       o**>t. 


, 
B 


5KONOAKY  MAIN 
VKTOKS 


FIG.  207. — Correct  method  of  connecting  two  transformers  between  the  phase 
wires  and  the  neutral  wire  of  a  three-phasr  system. 


Posinw:  ft>LAK/rr 


A        B 


N 


AA^   ^AAA 


SUPPLY  MAIN 

VECTORS 


4^€ 

4/c       t)***+i. 


.xsw 

^      ^^ 


>SECONQA*Y  MAIN 
vecrozs 


FIG.  208. — Incorrect  method  of  connecting  two  transformers  between  the  ph* 
wires  and  the  neutral  wire  of  a  three-phase  system. 


[  376  ] 


TRANSFORMERS 
A 


Sec.  6 


Jl/PPLY  MA/N 


wwww^      3 


TffANSFOifflfl? 


M- 


/AAAA^    3/\/\N\4 


A'  B'        C1          D' 


4*3 


srcoMOAfY  rrcroes 


K 


^zeroes 


D1- 

FIG.  209. — Transformer  connections  for  transforming  from  three-  to  two-phase. 


B  C 


AAAA? 


4          4      S      3 
3.      6     4 


A'  &'        C'          D 


•SecONOAKY  VKTOB3 


FIG.  210. — Transformer  connections  for  transforming  from  three-  to  two-phase. 

[  377  ] 


Sec.  6  TRANSFORMERS 

mary  and,  in  consequence,  the  voltages  between  A'  and  B',  and  C'  and 
D'  will  be  the  same  as  in  the  transformers  a  and  b. 

In  Fig.  210  the  secondary  voltages  are  reversed,  as  the  polarity 
of  the  transformers  is  negative  instead  of  positive,  and  it  is,  there- 
fore, impossible  to  parallel  the  transformers  as  illustrated  in  Figs. 
209  and  210  on  the  secondary  side.  If,  however,  A'  Fig.  209  is 
connected  to  B'  Fig.  210;  and  B'  Fig.  209  to  A'  Fig.  210;  C'  Fig.  209 
is  connected  to  D'  Fig.  210,  and  D'  Fig.  209  is  connected  to  C'  Fig. 
210,  and  providing  their  characteristics  are  the  same  the  trans- 
formers may  be  operated  in  parallel. 

37.  SCOTT  TRANSFORMATION   VECTOR  ANALYSIS   (Fig. 
211).    Illustrating  the  transformation  from  a  three-phase  system,  in 
which  the  delta  voltage  is  E  to  a  two-phase  system  in  which  the  phase 
voltage  is  E,  draw  an  equilateral  triangle  A,  B,  C  to  a  scale  pro- 
portional to  E,  which  represents  the  delta  voltage  of  the  three-phase 
system.     Draw  AO  from  the  point  A  to  the  center  of  BC,  which 
represents  the  voltage  on  the  three-phase  side  of  the  transformer  in 

/~~q  Tfl  -HI 

Fig.  209  and  is  equal  to  the  -^-J|-  X  E ;  OB  =  -— -  and  OC  =  -0-repre- 

J  &  A 

senting  respectively  the  voltages  impressed  on  the  windings  b  and 
c  of  the  transformer  illustrated  in  Fig.  209. 

Draw  OD  equal  to  CB.  This  represents  E  the  voltage  of  one 
phase  of  the  two-phase  system.  Draw  OF  equal  to  BC.  This 
represents  the  voltage  of  the  other  phase  of  the  two-phase  system. 

2 
The  ratio  of  OF  to  OA  is  equal  to  —7=..     Draw  Oa  at  an  angle  6  from 

A/3 

O A  representing  the  power  factor  on  the  three-phase  side  of  the  trans- 
former. The  length  of  Oa  is  proportional  to  the  load  current  I  on 
the  three-phase  side  of  the  transformer.  Draw  Oc  and  Od  propor- 
tional to  I,  each  120°  from  Oa.  These  represent  the  currents  flowing 
in  each  half  of  the  transformer  connected  to  B  C .  Since  the  ratio  of  OF 

2 

to  OAis  . the  current  flowing  in  the  two-phase  side  of  the  trans- 
former must  be  equal  to  I X  .  Lay  off  Ob  equal  to  this  value,  Ob 

2 

then  represents  in  value  and  phase  the  current  in  the  two-phase 
winding  of  the  transformer.  Connect  d  and  c,  then  drop  a  per- 
pendicular line  from  O  to  dc  bisecting  this  line  at  e.  Draw  Of 
parallel  to  dc  and  equal  to  ec.  This  represents  both  in  value  and  in 
phase  the  current  in  the  other  two-phase  winding  of  the  transformer, 

and  is  equal  to  I X  — — —- ,  one-half  dc  is  used,  as  the  difference  in  these 

two  currents  is  in  effect  only  flowing  through  one-half  of  the  coils  on 
the  three-phase  side  of  the  transformer. 

38.  THE    SPECIAL    SERIES    INCANDESCENT    LIGHTING 
TRANSFORMER    (Fig.  212)    is  a  constant  potential  transformer 

[  378  ] 


REGULATORS 


Sec.  6 


constructed  with  a  number  of  primary  taps,  by  the  use  of  which  it 
may  be  connected  to  primary  circuits  with  various  percentage  drops. 
Numerous  leads  are  also  brought  out  from  the  secondary  winding  to 
permit  its  connection  to  series  circuits,  in  which  the  numbers  of 
lamps  may  vary.  Each  lamp  is  supplied  with  a  small  inductance 
in  parallel  with  the  lamp  filament.  The  resistance  of  the  lamp 
filament  and  this  inductance  are  so  proportioned  that  when  the 
filament  is  intact  the  major  part  of  the  line  current  flows  through 
the  filament.  If,  however,  the  filament  is  broken  the  current  will 
flow  through  the  inductance  and  the  circuit  will  remain  closed. 

In  Fig.  212  the  current  is  shown  flowing  through  one  of  the  in- 
ductances at  a  location  where  the  filament  of  the  lamp  has  been 


FIG.  211. — Vector  analysis  of  three-phase,  two-phase  transformation. 

broken.  Under  such  conditions  the  voltage  across  each  lamp  and 
the  current  flowing  in  the  circuit  are  practically  the  same  as  when  all 
the  lamps  are  burning. 

The  power-factor  of  the  transformer  will  vary  with  the  number 
of  lamps  burning,  i.  e.  the  power-factor  will  be  lower  when  the  per- 
centage of  lamps  burning  is  small  than  when  all  are  burning. 

A  typical  regulation  curve  is  given  in  Fig.  213. 

Such  transformers  may  be  tested  in  a  manner  similar  to  the  method 
used  when  testing  commercial  power  and  lighting  transformers. 

INDUCTION  REGULATORS 

39.  General  Description.  The  induction  regulator  is  a  special 
type  of  transformer  built  like  an  induction  motor  with  a  coil-wound 

[  379  ] 


Sec.  6 


REGULATORS 


secondary,  which  is  used  for  varying  the  voltage  delivered  to  a  syn- 
chronous converter  or  alternating-current  feeder  system.  In 
comparison  with  a  variable  ratio  transformer  it  possesses  the  ad- 
vantage of  being  operated  without  opening  the  circuit  and  without 
short-circuiting  any  transformer  coil.  However,  it  has  a  larger 
magnetic  leakage  and  a  higher  value  of  exciting  current  than  a 
transformer  of  equal  capacity.  The  primary  of  the  induction  regula- 
tor is  subjected  to  the  constant  voltage  of  the  supply  system.  The 
delivered  voltage  being  varied  by  combining  with  the  supply  voltage 
the  e.  m.  f.  generated  inductively  in  the  secondary.  The  primary 
is  normally  at  rest,  although  it  is  movable  at  will  for  the  purpose  of 
varying  the  voltage. 

There  are  two  distinct  types  of  induction  regulators,  possessing 
different  inherent  characteristics  but  performing  similar  duties, 
namely,  the  single  phase  and  the  polyphase.  The  former  is  used  for 
single-phase  lighting  circuits  while  the  latter  is  generally  employed 
in  connection  with  rotary  converters  and  similar  apparatus. 

In  the  single-phase   induction   regulator   the  voltage   generated 


\\ 

fc  vl 


PRIMARY/ 

or  TRANS.,  WITH 

PERCENTAGE  TAPS 


S&H   n    n »n 


•COIL 


o 


o~  o 


•^BROKEN 
LAMP 


SECONDARY  or  TRANS., 

WITH  VARIOUS  TAPS  TO  rURNISH 
THE  EXACT  VOLTAGE  REQUIRED. 


Fia.  212.  —  Special  series  incandescent  lighting  transformer. 


in  the  secondary  varies  with  the  mechanical  position  of  the  rotor, 
but  the  voltage  at  all  times  remains  directly  in  time  phase  with  (or 
time  phase  opposition  to)  the  primary  e.  m.  f.  Thus  the  resultant 
delivered  e.  m.  f.  is  equal  to  the  arithmetical  sum  (or  difference)  of 
the  primary  and  the  secondary  e.  m.  f.  —  the  latter  depending  upon 
the  position  of  the  movable  element. 

Referring  now  to  the  diagrams  of  Figs.  214  and  215,  showing  the 
values  of  the  primary  and  secondary  electromotive  forces,  let  OA  be 
the  value  and  time  phase  position  of  the  e.  m.  f  .  of  the  primary  coil, 
and  let  OD  or  OE  be  the  maximum  value  of  the  e.  m.  f  .  of  the  second- 
ary; this  e.  m.  f.  may  be  either  subtracted  from  or  added  to  the 
primary  e.  m.  f  .  (according  to  the  mechanical  position  of  the  moving 
member)  in  order  to  produce  the  resultant  e.  m.  f.  If  now  the  line 
OE  be  allowed  to  represent  also  the  mechanical  position  (in  electrical 
space  degrees)  of  the  moving  member  when  the  maximum  secondary 
e.  m.  f.  is  additive  in  phase  with  the  primary  e.  m.  f.,  then  OD  (180 
electrical  space  degrees  from  OE)  is  the  mechanical  position  of  the 

[  380  ] 


REGULATORS 


Sec.  6 


moving  member  when  the  maximum  e.  m.  f.  is  subtractive  in  phase 
with  the  primary  e.  m.  f.  When  the  mechanical  position  of  the 
moving  member  is  OB  (Fig.  214)  the  secondary  e.  m.  f.  may  be  con- 
sidered to  have  the  value  OC  (CB  being  perpendicular  to  OD),  but 
it  remains  in  time  phase  (opposition)  with  OA,  so  that  the  resultant 
delivered  e.  m.  f.  is  CA>  similarly  when  the  mechanical  position  of 
the  moving  member  is  OB'  (Fig.  215)  the  secondary  e.  m.  f.  is  OC' 


10       20      30       40      JO       60       70       80       <?0      WO 
PeecENTAae  or  TOTAL  NUMBER  of  LAMPS  OUT. 
REGULATION  CuevE 

FIG.  213. — Typical  regulation    curve  of  the  special  series  incandescent  lighting 
transformer. 

and  it  is  in  time  phase  with  OA,  so  that  the  resultant  delivered 
e.  m.  f.  is  C'A. 

The  current  which  exists  in  the  secondary  of  the  single-phase 
induction  regulator  is  the  delivered  line  current,  which  depends 
inversely  upon  the  impedance  of  the  delivery  circuit  and  directly 
on  the  delivered  e.  m.  f.  The  load  current  in  the  primary  has  a 
value  such  that  its  magneto-motive-force  counter-balances  the 


1T 

r 

0 

o 

0 

o 

p 

>f* 

I/, 

4 

i 

FIG.  214. — E.   M.  F.  circuit   and  current  diagram  of  a  single-phase  induction 
regulator  in  a  negative  boost  position. 

demagnetizing  (or  magnetizing)  effect  of  the  secondary  current  on 
the  magnetic  core.  The  load  current  supplied  to  the  regulator 
circuit  is  the  arithmetical  sum  of  the  primary  and  secondary  currents 
when  the  secondary  e.  m.  f.  is  added  to  the  primary  e.  m.  f.  while 
it  is  the  arithmetical  difference  between  these  two  currents  when  the 
resultait  delivered  e.  m.  f.  is  the  difference  between  the  primary 
e.  m.  f.  and  the  secondary  e.  m.  f. 

[381] 


Sec.  6 


REGULATORS 


It  is  interesting  to  note  what  occurs  when  the  moving  member 
occupies  a  mechanical  position  90  electrical  space  degrees  from  the 
position  indicated  by  OD  or  OE  in  Figs.  214  and  215.  In  this 
position  the  value  of  the  secondary  e.  m.  f.  is  zero,  because  the  flux 
due  to  the  primary  exciting  current  passes  through  the  secondary 
core  parallel  to  the  secondary  windings.  The  resultant  delivered 
e.  m.  f .  is  therefore  equal  to  the  primary  e.  m.  f .  When  the  regulator 
is  in  use,  even  when  the  secondary  e.  m.  f .  is  of  zero  value,  the  second- 
ary current  may  have  the  full  load  value  because  it  depends  solely 
upon  the  delivered  e.  m.  f .  and  the  impedance  of  the  delivery  circuit. 
With  the  moving  member  in  the  position  here  assumed,  the  magneto- 
motive-force of  the  secondary  current  would  be  opposed  in  no  respect 
by  any  primary  current  so  that  a  large  value  of  flux  would  tend  to 
interlink  with  the  secondary  coil  and  produce  an  enormous  reactance 
therein.  To  overcome  this  defect  there  is  placed  upon  the  primary 
core,  in  electrical  space  quadrature  with  the  primary  coil,  a  separately 
insulated  coil  which  is  electrically  closed  upon  itself  and  forms  a 


74^  £   ^T 

[    "r   s3 

4?         0 
1                          0 

r/>              ° 

^ 

D 

P/>                     0 

\lp 

o 

\p 

T               ° 

r 

A^  ^          -^-1 

FIG.  215. — E.   M.   F.  circuit  and  current  diagram  of  a  single-phase    induction 
regulator  in  a  positive  boost  position. 

short  circuited  secondary  to  the  real  secondary  coil  of  the  regulator 
which  acts  as  its  primary  coil.  This  coil  may  be  referred  to  as  the 
tertiary  coil  of  the  regulator.  The  primary  and  the  tertiary  coils  are 
usually  placed  on  the  movable,  and  the  secondary  on  the  stationary 
member,  when  the  movable  member  of  the  regulator  is  in  the  maxi- 
mum, positive  boost  position  or  the  maximum  negative  boost  position 
(Figs.  214  and  215)  the  secondary  m.  m.  f.  is  directly  opposed  by  the 
primary  m.  m.  f.  and  no  current  is  produced  in  the  tertiary  coil. 
At  intermediate  positions  the  secondary  m.  m.  f .  is  opposed  in  part 
by  the  m.  m.  f.  of  current  in  the  primary  coil  and  partly  by  m.  m.  f. 
of  current  in  the  tertiary  coil;  the  resultant  of  these  two  m.  m.  f's. 
being  just  equal  to  the  secondary  m.  m.  f.  so  that  the  reactance  of 
the  secondary  is  reduced  to  that  due  to  the  magnetic  leakage  between 
the  stationary  and  the  movable  members. 

The  polyphase  induction  regulator  in  every  essential  detail  is 
a  polyphase  induction  motor  whose  polyphase  coil-wound  rotor  can 
be  locked  in  any  position  desired.  The  primary  windings  are  con- 
nected across  the  supply  lines  just  as  are  the  primary  windings  of  a 

[382] 


REGULATORS  Sec.  6 

polyphase  induction  motor;  however,  instead  of  being  closed  upon 
themselves  as  is  true  of  the  secondary  windings  of  an  induction  motor, 
the  secondary  windings  of  the  phases  of  the  induction  regulator  are 
separately  insulated  and  separately  connected  in  series  in  the  de- 
livery circuits  from  the  regulator.  When  polyphase  e.  m.  f.'s  are 
impressed  upon  the  primary  windings,  the  e.  m.  f.  generated  in  each 
secondary  coil  is  of  the  same  frequency  as  the  primary  e.  m.  f .  Its 
value  is  constant  and  entirely  independent  of  the  mechanical  position 
of  the  movable  member;  the  time-phase  position  of  these  e.  m.  f's., 
however,  varies  directly  with  the  electrical  space  position  of  the 
movable  member.  This  resultant  delivered  e.  m.  f.  is  the  vector 
sum  of  (or  difference  between)  the  primary  and  the  secondary  e.  m.  f's. : 
it  is  not  constant  in  value  but  varies  largely  with  the  position  of  the 
movable  member. 

Referring  to  Fig.  216,  let  OA  repiesent  the  e.  m.  f.  of  a  certain 
primary  phase  both  in  value  and  time-phase  position,  let  OE  (or  OD) 
represent  the  e.  m.  f.  of  the  corresponding  secondary  phase  winding 
in  the  maximum  positive  (or  maximum  negative)  boost  position. 
Let  OE  (or  OD)  simultaneously  represent  the  mechanical  position 
(in  electrical  space  degrees)  of  the  moving  member  when  the  second- 
ary e.  m.  f .  is  in  time-phase  with  (or  time-phase  opposition  to)  the 
primary  e.  m.  f.  In  any  mechanical  position  of  the  moving  member, 
such  as  OB,  the  secondary  e.  m.  f.  has  a  value  equal  to  OE  (or  OD) 
and  its  time-phase  position  is  correctly  represented  by  the  line  OB. 
This  fact  is  attributable  to  the  existence  of  a  revolving  field  produced 
by  the  combination  of  the  fluxes  of  the  separate  primary  phases. 
For  the  present  discussion  the  revolving  field  may  be  considered  to 
have  a  constant  strength,  so  that  the  time-phase  position  of  the 
e.  m.  f.  produced  in  any  conductor  subjected  to  this  field  will  vary 
directly  with  its  relative  electrical  space  position.  Since  in  Fig.  216 
the  primary  e.  m.  f.  is  OA  and  the  secondary  e.  m.  f.  is  OB  the  re- 
sultant e.  m.  f .  must  be  AB,  both  in  value  and  in  relative  time  phase 
position. 


E  O  D 

FIG.  216. — Vector  diagram  of  a  polyphase  induction  regulator. 

The  current  in  the  delivery  circuit  (which  is  the  same  as  that  in 
the  secondary  coil)  depends  directly  upon  the  resultant  delivered 
e.  m.  f.  and  the  impedance  of  the  delivery  circuit.  In  the  polyphase 
induction  regulator,  there  is  no  special  tertiary  circuit,  but  each 
primary  phase  winding  acts  in  part  as  the  tertiary  circuit  for  the 
remaining  primary  phase  windings  and  the  several  secondary  phase 
windings.  Thus  the  m.  m.  f .  of  the  current  in  any  secondary  phase 
winding  in  any  position  whatsoever  is  fully  counterbalanced  (except 
for  magnetic  leakage)  by  the  m.  m.  f.  of  the  current,  or  currents,  of 

[  383  ] 


Sec.  6  REGULATORS 

one  or  more  primary  phase  windings,  and  the  reactance  of  the  sec- 
ondary is  reduced  to  that  due  to  the  magnetic  leakage  between  the 
stationary  and  movable  members. 

40.  The  Pole  Type  Induction  Regulator  has  been  developed  in 
order  that  long  lightly  loaded  branch  feeders  may  be  connected  to 
heavily  loaded  main  feeders.  Unless  an  intermediate  voltage  con- 
trol is  installed,  regulation  on  such  a  branch  is  very  poor,  es- 
pecially when  connected  to  a  main  feeder  close  to  the  station. 

The  general  construction  of  the  regulator  is  illustrated  in  Figs. 
217  and  218. 

The  usual  regulator  construction  is  departed  from,  due  to  the 
small  amount  of  space  available.  See  Fig.  219.  The  stator  or 


FIG.  217. — Pole  type  induction  regulator  showing  cast  lugs  for  hanging  on  trans- 
former hooks. 

secondary  core  has  two  slots  only,  in  which  a  form  wound  coil  is 
placed.  The  rotor  or  primary  core  has  four  slots,  two  of  which 
are  occupied  by  a  single  primary  coil,  wound  directly  on  the  core. 
The  remaining  slots,  which  are  in  quadrature  with  the  slots  contain- 
ing the  primary  winding,  are  opposite  the  secondary  coil  in  Fig.  219. 
These  slots  contain  round  copper  rods  riveted  to  the  cast  brass 
flanges  located  at  the  top  and  bottom  of  the  rotor,  thus  clamping 
the  primary  punchings  and  also  acting  as  a  tertiary  coil.  The 
flanges  attached  to  these  brass  castings  hold  the  rotor  in  alignment. 
Diagrammatic  connections  are  illustrated  in  Fig.  220.  The 
rotor  is  operated  by  a  continuously  running  single-phase  motor,  by 

[384] 


REGULATORS 


Sec.  6 


means  of  a  ratchet  and  pawls.  A  voltage  relay  controls  the  pawls, 
so  that,  to  raise  the  voltage  the  ratchet  wheel  is  revolved  in  a  given 
direction  and  to  lower  the  voltage  in  an  opposite  direction.  The 
relay  is  designed  so  that  there  are  no  arcing  contacts. 

Such  regulators  are  built  in  10,  15,  25,  and  50  ampere  sizes,  for 
60  cycle  circuits  up  to  and  including  2300  volts.  The  range  of 
regulation  is  10%  above  or  below  normal.  The  motor  and  relay 
are  designed  to  operate  on  110  or  220  volts. 


FIG.  218. — View  of  mechanism  and  core  of  pole  type  induction  regulator. 

41.  INDUCTION  REGULATOR  TESTS  may  be  divided  as  follows: 

1.  The  Insulation  Test  is  made  in  a  manner  similar  to  such  tests 
for  transformers  (Figs.  174  and  175),  except  that  the  secondary  or 
stator  coils  should  be  tested  at  the  same  voltage  as  that  of  the  primary 
or  rotor  winding,  the  condition  under  which  they  normally  operate 
(Art.  23). 

2.  The  Heating  Test  can  be  simplified  as  it  is  not  necessary  to 
have  an  external  source  of  current  supply  to  circulate  the  loading 
current.     Full  load  conditions  may  be  obtained  when  testing  two 
regulators  of  the  same  general  characteristics  (Fig.  181)  by  setting 
13  [  385  ] 


Sec.  6 


REGULATORS 


the  rotating  elements  at  such  positions  as  to  cause  full  load  current 
to  flow. 

If  only  one  regulator  is  to  be  tested  the  rotating  element  may  be 
set  so  that  full  load  current  will  flow  in  the  short-circuited  secondary 
when  normal  voltage  is  impressed  upon  the  primary.  As  full  load 


SECONDARY 


FIG.  219. — Section  of  regulator  winding  and  core. 

conditions  are  not  obtained  in  the  primary,  this  is  an  approximate 
test. 

3.  Iron  Loss  Test  (Art.  25). 

4.  Resistance  Tests  (Art.  26). 

5.  Copper  Loss  Tests  and  Impedance  Tests  are  made  in  a  manner 

[  386  ] 


REGULATORS 


Sec.  6 


similar  to  that  for  transformers  (Art.  27),  except  that  they  should 
be  made  at  several  positions  in  the  mechanical  rotation  of  the 
primary  or  rotor. 


-Stcondoryof 
Loaa  QfstrWuting  Transformer 

FIG.  220. — Connection  diagram  of  pole  type  regulator. 

6.  The  Range  of  Regulation  may  be  determined  by  connecting  a 
voltmeter  to  the  secondary  winding  and  rotating  the  primary, 
operated  at  normal  voltage,  through  an  arc  large  enough  to  obtain 
readings  from  zero  to  a  maximum  value  as  indicated  on  the  volt- 
meter. The  values  thus  obtained  corrected  for  the  impedance  drop 
at  full  load  represent  one-half  the  total  range  of  the  regulator. 

Let 

Es  =  the  maximum  effective  value  of  the  regulator  secondary 

voltage. 

e  =the  percent  variation  in  voltage  from  no  load  to  full  load 
referred  to  full  load  voltage,  for  maximum  boost  position.  (This  is 
found  in  the  same  manner  as  for  transformers.  Art.  49,  Section 
7.) 

Then  the  range  of  the  regulator  is 

Range  in  volts  =  2  E3  (1— TsJ 


BIBLIOGRAPHY 

A.  I.  E.  E.,  July,  1909,  Mr.  L.  W.  Chubb. 
"     1910,  Mr.  H.  W.  Tobey. 
Publications  of  Various  Manufacturers. 

Pennsylvania  Electric  Association,  1912,  Mr.  F.  W.  Shackelford. 
Alternating  current,  Franklin  &  Williamson. 
Foster's  Electrical  Engineers'  Pocket  Book. 
Standard  Handbook  for  Electrical  Engineers. 
American  Electricians'  Handbook. 


[387] 


SECTION  6 


PART  II 


LIGHTNING  PHENOMENA  IN  CONNECTION 
WITH  ELECTRIC  CIRCUITS,  PROTEC- 
TIVE APPARATUS,  GROUNDING 


SECTION  6 

PART  II— LIGHTNING  PHENOMENA  IN  CONNECTION 

WITH  ELECTRIC  CIRCUITS,  PROTECTIVE 

APPARATUS,  GROUNDING 


TABLE  OF  CONTENTS 

ARTICLE 

Lightning  Phenomena  in  Connection  with  Electric  Circuits. 

General 1 

The  Electric  Charge 2 

An  Impulse  or  Traveling  Wave .- 3 

Standing  Waves 4 

High  Currents 5 

Protective  Apparatus 

General 6 

Multigap  or  Low  Equivalent  Arresters 7 

Compression  Type  Arresters 8 

Circuit  Breaker  Type  Arresters 9 

Aluminum  Cell  or  Electrolytic  Arresters 10 

Single  Gap  and  Multipath  Arresters 11 

Location  of  Lightning  Arresters 12 

Installation  of  Lightning  Arresters 13 

Horn  Arresters 14 

Choke  Coils 15 

Ground  Wires 16 

Switches 17 

Fuses 18 

The  Link  Fuse 19 

The  Enclosed  Cartridge  Fuse •. 20 

The  Expulsion  Fuse 21 

Grounding 

General 22 

Laws  of  the  Resistance  of  Pipe  Earth  Connections 23 

Making  the  Earth  Connections 24 

Testing  Grounds 25 


[391] 


LIGHTNING  PHENOMENA  IN  CONNECTION  WITH  ELEC- 
TRIC CIRCUITS 

1.  General.     The  phenomena  causing  trouble  in  electric  systems 
may  be  divided  into  three  general  classes. 

1st.    High  voltage.     (Art.  2-4.) 
2nd.  High  frequency.     (Art.  2-4.) 
3rd.    High  current.     (Art.  5.) 

In  any  system  of  energy  transmission  there  are  three  types  of 
phenomena  causing  strains;  namely,  steady  stresses,  impulses  or 
blows,  and  vibrations. 

In  an  electric  system  high  frequency  and  high  voltage  cause  the 
same  types  of  stresses;  namely, 

(a)  Steady  stress  or  gradual  electric  charge.     (Art.  2.) 

(b)  Impulse  or  traveling  wave.     (Art.  3.) 

(c)  Standing  wave  or  oscillation  and  surge.     (Art.  4.) 

2.  The  Electric  Charge.     The  total  potential  difference  between 
the  ground  and  an  electric  circuit,  may  gradually  rise  by  the  ac- 
cumulation of  an  electric  charge  in  the  circuit,  until  the  "lightning 
arresters  discharge  or  the  insulation  is  punctured,  depending  upon 
which  is  the  point  of  least  resistance. 

Some  of  the  factors  causing  such  a  steady  and  gradual  accumula- 
tion of  electric  charge  are: 

(a)  The  collection  of  static  charge  from  rain,  from  snow  drift, 
or  from  fog,  carried  by  wind  across  the  line.     The  presence 
of  accumulated  static  may  be  indicated  by  a  series  of  peri- 
odic lightning  arrester  discharges. 

(b)  An  accumulated  static  charge  may  follow  the  passing  of 
charged  clouds  due  to  electrostatic  induction.     Assuming 
for  instance,  a  charged  cloud  passing  over  a  transmission 
line.     The  ground  below  the  line  carries  an  electrostatic 
charge  of  opposite  sign,  corresponding  to  the  charge  of  the 
cloud.     The  line  should  have  a  charge  also,  higher  than  that 
of  the  ground  since  projecting  above  -it.     If  the  line  is 
insulated  from  ground,   without  the  charge  required  for 
electrostatic  equilibrium,  it  thus  appears  at  a  potential 
against  ground;  that  is,  at  cloud  potential.     With  the  ap- 
proach of  a  charged  cloud  to  the  transmission  line,  the  poten- 
tial of  the  line  against  ground  rises  until  a  discharge  takes 
place  between  the  ground  and  line,  charging  the  line  to 
ground  potential.     Inversely,  with  the  cloud  receding  from 
the  line,  the  line  charge  is  not  bound  by  the  charge  of  the 
cloud  and  therefore  discharges  to  ground. 

(c)  Potential  differences  between  the  line  and  ground  due  to 
differences   of   atmosphere   potential   in   different   regions 
traversed  by  the  line,  especially  so  if  the  line  passes  through 
different  altitudes. 


Sec.  6  PROTECTIVE  APPARATUS 

(d)  Accidental  electrostatic  charges  "entering  the  circuit  as  from 
frictional  electricity  from  belt-driven  machinery. 

(e)  Unsymmetrical  conditions  of  the  generator  potential  such 
as  the  grounding  of  a  wire  on  a  three-phase  system  which 
will  give  the  system,  as  a  whole,  an  alternating  potential 
difference  to  ground,  equal  to  the  voltage  between  a  phase 
wire  and  the  neutral  of  the  system. 

(f)  The  existence  of  higher  harmonics  in  the  electro-motive- 
force  wave  of  a  polyphase  system  may  cause  trouble  if  they 
are  of  such  an  order  that  they  coincide  in  the  different 
phases;  that  is,  the  whole  system  rises  and  falls  with  their 
frequency.     In   a    three-phase    system,   the   third,    ninth, 
fifteenth,  etc.,  harmonics  coincide. 

The  effects  of  steady  electrostatic  stress,  where  uni-directional, 
and  caused  by  external  agents  as  items  a  to  d  or  alternating  and 
caused  by  internal  agents,  as  items  e  and  f ,  appear  not  only  in  the 
circuits  in  which  they  originate,  but  in  circuits  electrostatically  con- 
nected to  them. 

The  danger  of  such  accumulations  of  potential  lies  in  their  lia- 
bility to  damage  the  insulation  of  the  system  by  puncture  or  by  their 
discharge,  producing  other  and  more  serious  disturbances. 

3.  An  impulse  or  traveling  wave  is  caused  by  sudden  local  electro- 
static charges  on  a  transmission  line,  such  as  a  lightning  stroke, 
induced  potential  caused  by  the  sudden  discharge  of  a  cloud,  or  any 
other  sudden  local  change  in  conditions.  This  wave  of  potential 
and  current  travels  along  the  line  just  as  a  water  wave  travels  over 
the  surface  of  the  ocean. 

The  wave  front  is  very  steep,  i.  e.,  has  high  voltage  at  the  point 
of  impact,  but  gradually  flattens  out,  and  if  the  line  is  of  unlimited 
length  ultimately  disappears. 

If  the  line  is  of  definite  length  the  wave  is  reflected  and  combines 
with  the  incoming  waves  to  form  a  system  of  nodes  and  maxima, 
called  standing  waves. 

When  apparatus  is  connected  to  the  line,  the  traveling  wave  di- 
vides, part  is  transmitted  and  part  is  reflected.  The  impulse  is 
thus  broken  up  into  a  number  of  secondary  impulses  and  local  stand- 
ing waves,  which  may  reach  much  higher  voltages  than  that  of  the 
traveling  wave. 

Impulses  or  traveling  waves  may  be  caused  by : 

(a)  Direct  or  secondary  lightning  strokes,  which  generally  do 
local  damage,  but  do  not  travel  far,  as  the  disturbance  is 
generally  confined  to  a  very  few  impulses  of  steep  wave 
front  but  of  short  extent. 

(b)  Electrostatic  induction  from  lightning  discharges.     While 
each  of  these  impulses  is  rarely  of  sufficient  power  to  do 
serious  damage,  due  to  their  frequency  of  recurrence,  they 
may  lead  to  the  production  of  destructive  internal  surges. 
Impulses  originating  thus  are  felt  more  generally  through 

[  394  ] 


PROTECTIVE  APPARATUS 


Sec.  6 


the  system,  but  do  not  cause  as  much  local  damage  as  those 
originating  from  direct  strokes. 

(c)  The  discharge  of  slowly  accumulated  potential  resulting 
in  a  series  of  successive  impulses. 

(d)  Any  spark  discharge  from  line  to  line  or  from  the  line  to 
ground. 

(e)  Arcing  grounds. 

(f)  Sudden  changes  of  load,  switching,  etc. 


\\ 


FIG.  221. 


\ 


FIG.   222. 


\\ 


FIG.   223. 


Impulses  may  be  caused  by  external  or  internal  disturbances. 
Items  a  and  b  may  be  classed  as  external  causes,  c  and  d  as  both 
external  and  internal  causes,  e  and  f  as  internal  causes. 

4.  Standing  waves  are  formed  when  a  wave  train  is  reflected,  as 
the  waves  neutralize  at  some  points  forming  a  node  and  add  at  other 

[  395  ] 


Sec.  6  PROTECTIVE  APPARATUS 

points  forming  a  wave  crest,  of  greater  or  less  amplitude  than  that  of 
the  original  wave,  depending  upon  the  phase  relations  of  the  original 
and  reflected  waves.  Fig.  221,  shows  these  waves  in  phase  opposi- 
tion; Fig.  222,  about  90  degrees  apart  in  phase,  and  Fig.  223  practi- 
cally in  phase.  In  each  figure  O  is  the  original  wave,  F  the  re- 
flected wave  and  P  the  resultant  wave. 

An  oscillation  is  the  phenomenon  by  which  the  flow  of  power  in 
an  electric  circuit  restores  its  equilibrium  after  a  disturbance  of  the 
circuit  conditions.  Any  circuit  disturbance  may,  and  usually  does, 
produce  an  oscillation  which  may  be  local  only,  that  is,  contain  only 
very  high  frequency  harmonics,  but  it  may  become  universal  by 
including  the  fundamental  and  its  lower  harmonics.  In  the  latter 
case  it  is  usually  called  a  surge. 

Some  of  the  typical  forms  of  oscillation  are : 

(a)  Spark  discharges  to  and  from  the  line  as  over  lightning 
arresters;    the  breaking  up  of  a  traveling  wave  entering 
the  station,  results  in  the  formation  of  very  high  frequency 
oscillations,  millions  of  cycles  per  second. 

(b)  Arcing  grounds  and  other  arc  discharges  to  ground  from  a 
line  of  an  insulated  system;    reflected  waves,  etc.,  give 
oscillations  which,  while  still  of  very  high  frequency,  are 
considerably  lower  in  frequency  than  item    (a),  that  is, 
hundred  thousand  of  cycles  per  second. 

(c)  Charge  and  discharge,  of  the  line  as  when  discharging  an 
accumulated  electric  charge  over  a  path  of  low  resistance; 
connecting  a  dead  transformer  to  the  line,  etc.,  results  in 
high  frequency  oscillations  containing  also  an  appreciable 
low  frequency  component. 

(d)  Sudden   changes  in  load,   connecting  or  disconnecting  a 
transmission  line;    opening  a  short  circuit  suddenly,  etc., 
give  oscillations  in  which  the  fundamental  frequency  pre- 
dominates. 

(e)  Low  frequency  surges,  consisting  primarily  of  the  funda- 
mental wave,  may  be  produced  by  certain  transformer  con- 
nections.    See  Art.  17,  Sec.  7. 

The  most  powerful  oscillation  is  the  short  circuit  surge  of  a 
system,  or  oscillation  produced  by  rupturing  a  short  circuit 
as  by  a  self -rupturing  arc. 

5.  High  currents  cause  damage  in  an  electrical  circuit  due  to  the 
intense  mechanical  strains  to  which  they  subject  the  apparatus. 
The  rapid  interruption  of  high  current  phenomenon  causes  high 
voltage  disturbances. 

PROTECTIVE  APPARATUS 

6.  General.     The   principal   protective   apparatus   for   overhead 
lines  may  be  divided  into  six  general  divisions  as  follows: 

1.  Lightning  Arresters.     (Arts.  7  to  11.) 

2.  Horn  Arresters.     (Art.  14.) 

[  396  ] 


PROTECTIVE  APPARATUS  Sec.  6 

3.  Choke  Coils.     (Art.  15.) 

4.  Ground  Wires  and  Lightning  Rods.     (Art.  16.) 

5.  Insulator  Protectors.     (Art.  27,  Sec.  5.) 

6.  Switches  and  Fuses.     (Art.  17,  18-21.) 

Lightning  Arresters.  The  function  of  a  lightning  arrester  is  two- 
fold; to  discharge  any  high  voltage  disturbance  that  may  occur  on  a 
line  and  to  accomplish  this  while  preventing  the  formation  of  a 
power  arc  which  may  cause  greater  voltages  by  oscillation,  or  which 
may  interrupt  service  by  forming  a  short  circuit  on  the  system. 

(a)  Multigap  or  Low  Equivalent  Arresters.     (Art.  7.) 

(b)  Compression  Type  Arresters.     (Art.  8.) 

(c)  Circuit  Breaker  Type  Arresters.     (Art.  9.) 

(d)  Aluminum  Cell  or  Electrolytic  Arresters.     (Art.  10.) 

(e)  Single  gap  and  Multipath  Arresters.     (Art.  11.) 

7.  MULTIGAP  OR  LOW  EQUIVALENT   ARRESTERS.     The 

general  theory  of  this  arrester  is  as  follows :  When  voltage  is  applied 
across  a  series  of  multigap  cylinders,  the  voltage  distribution  is  not  un- 
iform. There  is  a  capacity  effect  between  the  cylinders  and  from  each 
cylinder  to  ground,  which  concentrates  the  voltage  across  the  gaps 
nearest  the  line.  When  the  voltage  across  the  end  gaps  reaches 
a  certain  value,  they  arc  across,  passing  the  strain  back  to  the  other 
gaps,  which  in  turn  arc-over  until  the  spark  has  passed  entirely 
across  the  arrester.  The  arrester  thus  arcs  over  at  a  lower  voltage 
than  if  the  voltage  were  evenly  distributed  across  the  gaps. 

When  the  arresters  have  arced  over  and  current  is  flowing,  the 
voltage  is  evenly  distributed  between  the  gaps  and  for  this  reason 
is  too  low  to  maintain  an  alternating  current  arc.  The  arc,  there- 
fore, lasts  only  to  the  end  of  the  half  cycle  and  then  goes  out.  Alloys 
of  metals  with  high  and  low  boiling  points  are  used  for  lightning 
arrester  cylinder  gaps.  The  metals  with  low  boiling  points  tend  to 
cool  the  arc  while  the  metals  with  high  boiling  points  tend  to  pre- 
serve the  shape  of  the  cylinder  gaps. 

In  addition  to  the  cooling  effect  of  the  cylinders,  the  temperature 
of  the  arc  is  affected  by  the  amount  of  current  flowing,  which 
amount  may  be  limited  by  the  use  of  resistances. 

If  some  of  the  gaps  are  shunted  by  a  resistance  high  frequency 
disturbances  will  pass  directly  across  the  gaps,  but  the  dynamic  cur- 
rent will  pass  through  the  resistance  and  be  limited.  By  using  graded 
resistances  connected  to  different  gap  cylinders  the  arrester  may  be 
designed  to  care  for  high  frequency  and  low  frequency  disturbances 
equally  well.  This  type  of  arrester  is  illustrated  in  Figs.  224  and  225. 

This  effect  can  be  still  further  intensified  with  good  results  by 
bringing  a  connection  at  or  near  ground  potential,  near  the  series 
gaps,  thus  increasing  the  capacity  current  across  the  upper  gap  and 
lowering  the  breakdown  voltage.  An  arrester  embodying  this 
feature  is  shown  in  Fig.  226.  It  consists  essentially  of  a  number  of 
non-arcing  metal  cups,  insulated  from  each  other  by  porcelain  spacers 
and  connected  in  series  with  a  resistance  rod.  Through  the  center  of 
the  metal  cups  passes  a  metal  rod  connected  to  the  bottom  cup  but 

[  397  ] 


Sec.  6 


PROTECTIVE  APPARATUS 


[  398  ] 


PROTECTIVE  APPARATUS 


Sec.  6 


thoroughly  insulated  from  all  others.  The  electrostatic  effect  of  the 
close  proximity  of  this  rod  to  the  upper  cups  causes  the  breakdown 
voltage  of  these  gaps  to  be  greatly  lowered,  and  permits  the  use  of 
more  series  gaps  than  would  be  possible  were  the  control  rod  not 
present.  The  upper  end  of  the  rod  is  cemented  into  an  insulator 
having  a  cap  with  a  cast-in  eye  by  which  the  arrester  may  be  sus- 
pended. The  lower  end  of  the  arrester  carries  a  hook,  to  which 
another  arrester  can  be  attached  when  two  in  series  are  needed  for 
high  voltage  lines.  Good  contact  with  the  resistance  rod  is  insured 
by  a  spring  shunted  by  a  flexible  lead  inside  of  the  tube  which  en- 
closes the  resistance  rod.  This  arrester  may  be  used  outdoors,  and 


FIG.  226. — Low  equivalent  lightning  arrester,  single  pole. 

for  this  service  is  equipped  with  a  metal  rain  shield  over  the  spark 
gaps. 

8.  COMPRESSION  TYPE  ARRESTER.  The  compression  type 
arrester  is  a  particular  design  of  the  Multigap  arrester. 

Fig.  227  illustrates  the  arrangement  of  the  parts  of  the  compression 
chamber  arrester.  On  the  outside,  there  is  a  porcelain  base  with 
four  screw  holes  to  connect  it  to  a  cross-arm.  Immediately  inside  of 
this  base  are  the  antennae.  The  antennae  vary  in  form  in  different 
arresters,  but  as  illustrated  they  consist  of  two  metal  strips  in  the 
form  of  a  "U"  that  fit  inside  of  the  holder  or  base.  Inside  of  the 
antennae  is  placed  a  straight  porcelain  tube.  The  porcelain  tube  is 
held  in  place  by  insulating  cement.  Inside  of  the  porcelain  tube  the 
gap  units  are  placed.  Each  gap  unit  consists  of  two  punched  metal 
hats  of  special  alloy.  The  crowns  of  these  hats  are  turned  so  they 
face  each  other,  and  both  crowns  are  knurled.  Between  the  rims 
of  the  two  metal  hats  there  is  a  short  porcelain  tube  which  holds  the 
crowns  of  the  metal  hats  about  -fa*  (0.9  mm.)  apart.  These  gap 

[399] 


Sec.  6 


PROTECTIVE  APPARATUS 


units  are  stacked  one  on  top  of  the  other  inside  the  porcelain  tube 
between  the  arms  of  the  antenna?. 

On  top  of  the  gap  units  is  placed  a  resistance  rod  of  low  ohmic 
value.  The  gap  units  and  resistance  rods  fill  the  long  porcelain 
tube.  On  top  of  the  resistance  rod  a  spring  contact  is  made,  and  a 
porcelain  cap  is  fitted  over  the  end  of  the  tube  and  cemented  thereto. 
The  connecting  wire  projects  through  the  porcelain  cap.  The 
ground  connection  is  a  wire  which  passes  through  the  bottom  of  the 
base  and  is  connected  to  the  antenna  as  well  as  to  the  lower  gap 
unit.  The  arrester  is  hermetically  sealed  so  that  no  dust,  dirt  or 
moisture  can  enter. 

Due  to  the  effect  of  the  antenna?  in  this  arrester,  it  is  possible  to 


LINE  LEAD 


SWING  CONTACT 


COM  POUND - 


PORCELAIN  ^EPAKATOR 


GfOI/ND  LEAD 


© 


PORCELAIN  CA? 


-RESISTANCE  ROD 

— PORCELAIN  BASE 
—ANTENNA 


-METAL  ELECT/WOE 


FIG.  227. — Compression  type  arrester. 

use  more  than  the  usual  number  of  gaps  in  series.  In  consequence 
the  resistance  in  series  with  the  gaps  may  be  very  low  in  value. 
The  average  value  of  this  resistance  is  23  ohms.  The  discharge 
current  to  ground  per  phase  will  be  approximately  equal  to  the 
lightning  potential  divided  by  23  ohms. 

The  use  of  the  antennae  gives  uniformity  in  the  spark  potential 
regardless  of  the  surroundings;  its  use  also  reduces  the  spark  po- 
tential of  the  series  of  gaps  used  in  this  arrester,  to  exactly  one-half 
the  spark  potential  without  the  antenna?.  This  permits  the  use  of 
twice  as  many  gaps  as  would  otherwise  be  possible.  Each  gap  has 
the  function  of  extinguishing  a  certain  potential  applied  to  it.  There- 

[400] 


PROTECTIVE  APPARATUS  Sec.  6 

fore,  when  the  number  of  gaps  is  doubled,  the  arc-extinguishing 
power  of  the  arrester  is  greatly  magnified. 

Each  gap  is  enclosed  in  a  sealed  chamber,  and  any  expansion  of 
gases  in  that  chamber  will  cause  an  increase  in  pressure,  which 
tends  to  extinguish  an  arc.  Furthermore  the  porcelain  tube  which 
encloses  the  gap  has  its  cooling  surface  in  close  proximity  to  the  arc. 

Another  arrester  operating  on  the  compression  principle  is  de- 
scribed as  follows :  This  arrester  is  sometimes  used  for  the  protec- 
tion of  series  D.  C.  arc  circuits.  It  consists  of  two  sets  of  metal 
electrodes  mounted  flush  with  the  surface  of  a  lignum  vitae  block. 
Charred  or  carbonized  shallow  grooves  provide  a  ready  path  for  the 
discharge,  while  a  second  block,  fitting  closely  over  the  first  block, 
confines  the  discharge  and  limits  the  formation  of  gases  and  vapors. 
Such  gases  as  do  form  are  highly  compressed  and  are  expelled 
violently  through  grooves  transverse  to  the  discharge  path,  thus 
rupturing  the  arc.  As  no  series  resistance  is  used  with  this  arrester 
it  has  great  freedom  of  discharge. 

9.  CIRCUIT  BREAKER  TYPE  ARRESTER.  This  type  of  arrester 

is  illustrated  in  Fig.  228  and  consists  essentially  of  the  combination  of 
small  air  gaps,  low  series  resistance  and  a  mechanical  circuit  breaker. 

High  frequency  disturbances  enter  the  arrester  at  line  connection 
A,  and  pass  to  ground  across  gaps  B  and  C,  resistance  rod  D,  and  gaps 
E  and  F.  Coil  H  and  the  mechanical  circuit  breaker  are  connected 
in  multiple  with  the  gaps  E  and  F.  This  shunt  path  is  of  lower 
resistance  than  these  gaps,  but  has  a  higher  inductive  or  choking 
effect.  The  coil  will  therefore  shunt  any  dynamic  current  following 
the  discharge  to  ground  from  gaps  E  and  F.  High  frequency  dis- 
turbances, however,  will  not  flow  through  this  highly  inductive  shunt 
path,  but  will  take  the  path  across  gaps  E  and  F. 

When  the  flow  of  dynamic  current  following  the  discharge  to 
ground  through  the  arrester  is  small,  it  is  cut  off  by  the  action  of  the 
air  gaps  B,  C,  E,  and  F  as  the  voltage  wave  crosses  zero  value.  Under 
these  conditions,  the  arc  lasts  only  to  the  end  of  the  half  cycle  and 
then  dies  out.  These  discharge  electrodes  are  made  of  alloys  of 
metals  with  high  and  low  boiling  points.  The  metals  of  low  boiling 
points  vaporize  under  the  dynamic  arc  and  tend  to  cool  the  gaps, 
while  the  metals  of  high  boiling  points  tend  to*  preserve  the  shapes 
of  the  discharge  electrodes. 

Whenever  the  flow  of  dynamic  current  to  ground  exceeds  the  values 
that  will  be  cut  off  by  the  air  gaps  alone,  this  heavier  flow  is  shunted 
from  gaps  E  and  F  due  to  the  low  resistance  of  coil  H;  flows  through 
the  coil  and  so  produces  a  magnetic  field  which  raises  the  plunger  J, 
thus  cutting  off  the  current  inside  the  fiber  tube  and  extinguishing 
the  arc.  The  path  of  this  dynamic  current  is  indicated  by  the  dashed 
lines. 

These  arresters  may  be  used  for  higher  voltages  than  that  of  each 
unit  (Fig.  229)  by  connecting  the  units  in  series  as  shown  in  Fig.  230. 

For  pole  work  the  arresters  are  mounted  in  wood  boxes,  and  are 
usually  supported  from  the  arms  by  iron  hangers. 

[401] 


Sec.  6 


PROTECTIVE  APPARATUS 


B 


£•; 


[402] 


PROTECTIVE  APPARATUS 


Sec.  6 


10.  ALUMINUM  CELL  OR  ELECTROLYTIC  ARRESTERS. 

The  aluminum  cell  arrester  consists  of  plates  of  aluminum  arranged 
as  electrodes  of  a  battery.  The  electrolyte  may  be  anyone  of  a 
number  of  solutions.  When  current  passes  through  an  aluminum 
cell,  an  insulating  film  forms  on  the  surface  of  the  metal.  This  film 
has  a  certain  dielectric  strength.  If  the  voltage  rises  above  the 
critical  value,  current  can  flow  through  the  cell  with  very  little  im- 
pedance. 

When  the  line  has  been  relieved  of  disturbances  the  voltage  falls 
to  the  normal  value  (below  the  critical  voltage  of  the  arrester),  and 
the  film  at  once  reforms  and  shuts  off  the  current  flow.  If  an  alter- 
nating voltage  with  a  maximum  value  above  the  critical  voltage  of 
the  cell  is  impressed  across  an  arrester,  the  peak  of  each  voltage 
wave  will  be  cut  off  by  the  arrester. 


400 

^  320 

I 

I 

\~ 

§  so 

•t 

I 

1 

f- 

'                 /                 23                 4                 6 

FIG.  231. — Characteristic  curve  of  aluminum  cell  or  electrolytic  lightning  arrester 
for  alternating  current. 


The  volt-ampere  characteristic  curve  (Fig.  231)  of  the  aluminum 
cell  will  vary  somewhat  according  to  whether  direct  or  alternating 
currents  are  used. 

A  comparatively  low  voltage  arrester  is  illustrated  in  Fig.  232, 
while  in  Fig.  233  is  illustrated  an  arrester  for  high  voltage  lines. 
WThen  an  aluminum  cell  arrester  is  disconnected  from  the  circuit 
for  any  great  length  of  time,  part  of  the  filrn  is  dissovled  and 
when  reconnected  to  the  circuit  there  is  a  momentary  rush  of  current 
which  reforms  the  film.  The  value  of  this  current  depends  upon  the 
length  of  time  the  arrester  is  disconnected  from  the  circuit. 

To  prevent  this  film  dissolution,  it  is  advisable  to  charge  the 
arrester  once  every  twenty-four  (24)  hours,  which  may  be  accom- 
plished by  short-circuiting  the  gaps.  Where  it  is  deemed  necessary 
resistance  may  be  inserted  to  damp  out  oscillations  resulting  from 
charging,  or  to  reduce  the  initial  rush  of  current.  Horn  gaps  with 
charging  resistance  are  shown  in  Figs.  234,  235. 

When  the  arrester  cells  are  so  assembled  that  one  section  is  not 
connected  directly  to  the  line  when  charging,  it  is  necessary  to  install 
a  transfer  or  reversing  switch  connecting  this  section  and  one  of  the 
line  sections  so  that  the  relative  connections  of  the  sections  may  be 

[403] 


Sec.  6 


PROTECTIVE  APPARATUS 


reversed.     The  films  on  all  the  cells  may  thus  be  formed  to  the  same 
critical  voltage  value. 

11.  SINGLE  GAP  AND  MULTIPATH  ARRESTERS.  A  type  of 
low  voltage  arrester  is  shown  in  Fig.  236.  This  type  consists  of  two 
heavily  beaded  brass  discs,  A  and  B,  separated  from  each  other  at  the 
beads  by  a  -fa  inch  air  gap  by  means  of  a  high  resistance  disc  C.  Wires 
P  and  E  are  soldered  to  these  discs,  one  of  which  is  connected  to  the 
line  wire,  the  other  to  the  ground. 


FIG.  232. — Three  pole 

electrolytic    lightning 

arrester  for  thee-phase 

6,600  volt  circuits. 


FIG,  233. — Single  pole  aluminum  cell  lightning 
arrester  for  110,000  volt  circuits. 


Light  charges  of  lightning  and  of  accumulated  static  find  a  path 
from  line  to  ground  by  leaking  through  this  high  resistance  disc. 
When  subjected  to  a  heavier  charge  the  high  resistance  disc  prevents 
the  charge  leaking  to  ground  quickly  enough;  hence,  these  heavier 
charges  jump  across  the  -£$  inch  air  gap  to  ground. 

[404] 


PROTECTIVE  APPARATUS 


Sec.  6 


!! 


[405] 


Sec.  6 


PROTECTIVE  APPARATUS 


The  flow  of  line  current  following  the  high  potential  discharge  to 
ground  is  usually  very  small,  and  when  the  voltage  of  the  circuit 
crosses  zero  value,  the  arc  dies  out.  The  metallic  beads  being  large 
and  cool,  cool  the  arc  vapors  to  such  an  extent  that  when  the  voltage 


FIG.  236. — Diagrammatic  view  of  single  gap  lightning  arrester. 

wave  builds  up  to  a  maximum  value,  the  voltage  is  not  sufficient  to 
again  start  an  arc  at  the  air  gap. 

The  assembled  arrester  is  illustrated  in  Fig.  237. 


FIG.  237. — Single  gap  lightning  arrester. 

The  multipath  arrester  (Fig.  238)  consists  of  a  carborundum 
block  enclosed  in  a  cast  iron  shell  or  box.  A  small  spark  gap  of 
slightly  over  ^th  of  an  inch,  mounted  inside  of  the  case  in  series 
with  the  carborundum  block,  serves  to  keep  the  latter  normally 

[  406  ] 


PROTECTIVE  APPARATUS 


Sec.  6 


insulated  from  the  line.  The  terminals  to  the  circuit  and  the  ground 
connection  are  attached  to  metal  plates  on  either  side  of  the  block 
and  all  discharges  must  pass  between  them.  . 

The  static  discharge  spreads  itself  over  the  carborundum  block 
along  a  number  of  minute  discharge  paths  (multipath).  The  voltage 
across  each  gap  is  very  low;  therefore,  the  line  voltage  cannot  main- 
tain an  arc  across  them.  The  action  is  analogous  to  that  of  a 
coherer  in  wireless  telegraphy  in  that  the  body  of  the  block  becomes 
momentarily  conducting  as  a  result  of  the  shock  given  the  slightly 
separated  particles.  Thus,  while  the  ohmic  resistance  to  slowly 
applied  low  potentials  is  several  megohms,  the  equivalent  spark  gap 
is  very  low.  These  arresters  are  single  pole  and  may  be  mounted  on 
a  pole  or  used  in  the  station,  and  are  suitable  for  eithe^  alternating 
current  or  direct  current  circuits  up  to  1000  volts. 


FIG.  238. — Multipatn  lightning  arrescer. 


12.  LOCATION   OF  LIGHTNING   ARRESTERS.     No  general 
rule  can  be  made  governing  the  required  number  or  the  spacing  of 
lightning  arresters.     Installations  sufficient  to 'give  protection  in 
some  localities  will  give  insufficient  protection  in  others. 

The  factors  governing  the  location  of  lightning  arresters  are: 
the  intensity  and  frequency  of  lightning  storms,  the  location  of  the 
line  in  relation  to  natural  protective  features,  such  as  tall  trees,  build- 
ings, conditions  of  altitudes,  etc.,  the  potential  of  the  line,  since  a 
lightning  disturbance  that  may  cause  damage  on  a  low  voltage  line 
may  be  unnoticed  on  one  of  higher  potential. 

13.  INSTALLATION  OF  LIGHTNING  ARRESTERS.    The  wir- 
ing connections  of  lightning  arresters  are  of  utmost  importance.   The 
discharge  circuit  should  contain  minimum  impedance,  and  hence  must 
furnish  the  shortest  and  most  direct  path  from  the  line  to  ground.  The 
most  severe  disturbances  which  an  arrester  is  called  upon  to  handle 

[  407  ] 


Sec.  6 


PROTECTIVE  APPARATUS 


are  those  of  high  frequencies,  and  it  is  therefore,  imperative  to  elim- 
inate all  unnecessary  inductance.  The  features  favorable  tojlow  in- 
ductance are  short  length  of  conductor,  large  radius  bends  and  a  con- 
ductor or  large  surface  area.  For  wiring  high  voltage  arresters  the 
use  of  copper  tubing  is  strongly  recommended.  Such  copper  tubing 


has  the  advantage  over  either  copper  strip  or  solid  conductors  in 
that  it  is  easily  supported,  requires  fewer  insulators,  and  is,  therefore, 
cheaper  to  install.  Copper  tubing  connections  can  be  designed  so 
that  all  sharp  bends  are  eliminated  and  there  are  no  points  where 
corona  or  brush  discharge  may  take  place. 

The  wiring  for  pole  type  arresters  should  never  be  wound  in  a  spiral 

[  408  ] 


PROTECTIVE  APPARATUS  Sec.  6 

coil.  If  this  is  done,  the  usefulness  of  the  arrester  is  practically 
counteracted  by  the  inductance  of  the  wire  coil.  Even  one  turn  will 
greatly  reduce  the  effectiveness  of  the  arrester  and  in  some  cases 
may  entirely  prevent  its  discharge.  The  wiring  from  the  arrester 
to  the  ground  should  be  as  short  and  straight  as  possible.  This 
connection  may  be  made  by  copper  wire,  rod,  or  strap,  and  should  be 
protected  by  a  wood  cover  extending  from  the  ground  line  to  a  point 
seven  feet  above. 

When  an  iron  pipe  ground  is  made,  the  copper  connection  from  the 
arrester  to  the  pipe  should  be  securely  fastened  to  the  top  of  the  pipe 
and  not  carried  down  the  inside  of  the  pipe. 


FIG.  240. — Horn  gap  lightning  arrester  combined  with  choke   coil   for   constant 
potential  circuits. 

The  wire  should  not  be  wound  around  the  pipe  before  connecting 
thereto. 

Lightning  arrester  grounds  should  be  kept  separate  from  all  other 
grounds. 

For  methods  of  making  grounds,  see  Arts.  22,  23,  24  and  25. 

14.  HORN  ARRESTERS.  Horn  arresters  should  not  be  consid- 
ered as  true  lightning  arresters,  but  rather  an  insulation  intentionally 
weak.  If— -due,  for  instance  to  direct  stroke — the  insulation  of  a  line 
must  fail,  it  is  much  more  preferable  that  it  should  do  so  over  a  horn 

[  409  ] 


Sec.  6 


PROTECTIVE  APPARATUS 


arrester.  Horn  arresters  with  resistance  are  usually  useless,  except 
on  constant  current  circuits,  as  the  current  of  discharge  is  too  limited 
to  relieve  the  line.  With  no  resistance,  or  with  resistance  low  enough 
to  relieve  the  line,  synchronous  apparatus  will  be  thrown  out  of 


FIG.  241.— -Choke  coil. 


step  and  the  line  shut  down  before  the  arc  can  be  extinguished. 
The  line,  however,  can  be  immediately  put  into  service  again,  which 
could  not  be  done  if  the  insulation  was  punctured.  The  place  for 


FIG.  242.— Choke  coil. 

horns,  therefore,  is  along  the  pole  line  at  short  intervals,  setting  the 
gaps  for  very  high  voltage  arc-over. 

For  constant  current  arc  lamp  circuits,  horns  form  an  excellent 

[410] 


PROTECTIVE  APPARATUS 


Sec.  6 


arrester,  as  only  a  small  current  is  required  to  relieve  the  line,  and 
resistance  can  be  used.  For  mercury  arc  rectifier  arc-lamp  circuits, 
this  arrester  is  especially  well  adapted,  as  the  multigap  arrester  will 
not  operate  on  direct  current. 

A  typical  horn  arrester  is  shown  in  Fig.  239,  and  a  type  combining 
the  horn  gap  and  choke  coil  is  shown  in  Fig.  240. 

15.  CHOKE  COILS  or  reactances  have  the  function  of  retarding 
high  frequency  disturbances,  thus  giving  the  lightning  arresters  an 
opportunity  to  relieve  high  potential  stresses  before  they  enter  the 
apparatus.     Choke  coils  are  not  effective  in  retarding  low  frequency 
disturbances.    Several  types  of  choke  coils  are  illustrated  in  Figs.  241, 
242,  243. 

16.  GROUND  WIRES  AND  LIGHTNING  RODS.  Wire  conduc- 
tors placed  underground  or  insulated  wire  conductors  surrounded  by 
a  metallic  sheath  and  hung  overhead  are  protected  from  electrostatic 


FIG.  243.— Choke  coil 


charges  due  to  cloud  lightning.  As  it  is  generally  impractical  to  sur- 
round the  wire  conductor  by  a  metallic  sheath  the  next  best  thing  to 
do  is  to  place  some  object  at  ground  potential  over  the  line.  This  may 
be  done  by  stringing  a  grounded  wire  over  the  line.  The  greater  the 
distance  between  the  grounded  wire  and  the  line,  the  better  partial 
protection  is  afforded  the  line.  Dr.  Steinmetz  recommends  that  an 
overhead  grounded  wire  be  so  placed  that  two  imaginary  lines  drawn 
from  this  wire  45°  down  from  the  horizontal  will  include'  all  line  wires 
between  them.  Each  additional  overhead  ground  wire,  properly 
placed,  gives  some  additional  protection  against  induced  static 
electricity  from  the  clouds. 

The  overhead  grounded  wire  also  has  the  function  of  protecting 
wood  poles  from  being  shattered  by  a  direct  stroke  of  cloud  lightning. 
It  also  has  the  possibility  of  carrying  a  direct  stroke  of  cloud  lightning 
to  ground,  past  the  line  wires,  without  shattering  the  insulators  or 
causing  a  short  circuit. 

[411] 


Sec.  6 


PROTECTIVE  APPARATUS 


FIG.  244.— Air  break  3  P.  S.  T.  switch. 


FIG.  245. — Air  break  S.  P.  S.  T.  disconnecting  switch  for  300  amperes  and  35,000 

volts. 


FIG.  246.— Air  break  S.  P.  S.  T.  disconnecting  switch  for  300  amperes  and  90,000 

volts. 

[  412  ] 


PROTECTIVE  APPARATUS 


Sec.  6 


Lightning  rods  at  each  pole  will  add  a  slight  probability  that  a 
direct  stroke  will  strike  at  the  pole  and  not  between  poles. 

If  the  overhead  grounded  wire  is  earthed  at  every  pole,  direct 
strokes  of  lightning  are  likely  to  find  a  more  direct  path  to  earth. 
The  wave  front  of  a  direct  stroke  is  usually  so  steep  that  the  charge 
finds  the  natural  inductance  of  the  horizontal  wire  a  great  im- 
pedance, and  consequently  it  is  likely  to  side-flash  to  other  lines  and 
also  over  insulators  to  its  natural  terminum,  the  earth.  If  the  earth 
connection  is  made  at  every  third  pole  instead  of  at  every  pole,  there 
is  a  possibility  that  a  direct  stroke  will  hit  a  midway  point  and  have 
a  greater  distance  to  travel,  parallel  to  the  line  wire,  before  it  reaches 
the  earth.  The  parallel  movement  of  the  charge  gives  electromag- 
netic induction  on  the  power  wires.  Practically  all  reports  of  dam- 
ages to  lines  by  direct  strokes  confine  the  line  damage  to  about  seven 


FIG.  247. — Horn  gap  air  break  S.  P.  S.  T.  switch  for  300  amperes  and  44,000  volts. 

successive  poles.  Therefore,  a  close  study  of  operating  conditions 
should  be  made  in  order  to  determine  the  necessity  for  frequent 
earth  connections. 

17.  SWITCHES.  Switches  may  be  divided  into  two  general 
groups. 

1.  Air  break  switches. 

2.  Oil  switches. 

Air  break  switches  are  usually  used  as  disconnecting  switches  and 
on  lines  of  low  amperage  capacity  may  be  used  to  open  a  loaded  cir- 
cuit or  branch  line.  They  are  seldom  used,  however,  to  break  short 
circuit  currents.  Several  types  of  air  break  switches  are  illustrated 
in  Figs.  244-247.  When  air  break  switches  are  used  in  connection 
with  series  circuits  they  take  the  forms  illustrated  in  Figs.  248  to  251. 

[413] 


Sec.  6  PROTECTIVE  APPARATUS 

The  switches  illustrated  in  Figs.  248-249  are  used  in  connection 
with  individual  arc  lamps  and  are  so  arranged  that  each  unit  may  be 
completely  disconnected  from  the  circuit  without  interrupting  the 
passage  of  current.  The  switches  illustrated  in  Figs.  250  and  251 
serve  the  purpose  of  disconnecting  a  number  of  units  simultaneously 
and  are  so  arranged  that  both  the  main  circuit  and  the  disconnected 
loop  are  closed,  thus  permitting  the  operation  of  the  remaining 
portion  of  the  series  circuit  when  the  loop  has  been  disconnected. 

Fig.  250  is  a  non-automatic  switch,  while  Fig.  251  is  an  automatic 
switch,  the  operation  of  which  is  as  follows: 


FIG.  248. — Absolute  arc  lamp  cutout. 

Let  the  circuit  under  normal  conditions,  which  starts  from  the 
terminal  T  of  a  constant  current  dynamo  or  constant  current  trans- 
former, pass  through  the  series  lamps  L,  etc.,  along  the  flexible  con- 
ductor J,  to  the  laminated  contact  B  and  contact  plate  C,  through 
the  lamps  N,  N,  etc.,  to  contact  plate  C'  and  laminated  contact  B', 
along  flexible  conductor  J',  through  balance  of  lamps  L,  etc.,  to  ter- 
minal T'  of  the  dynamo  or  transformer. 

The  section  of  the  above  circuit  which  is  being  protected  by  the 
automatic  series  cut-out,  extends  from  contact  plate  C,  through 
lamps  N,  N,  etc.,  to  contact  plate  C'. 

Let  a  break  occur  in  the  circuit  protected  by  the  cut-out,  say  at  O. 
Immediately  the  full  potential  difference  of  the  line  will  exist  across 
the  adjustable  gap  G  between  the  carbons  E  and  E',  the  carbons 
being  so  adjusted  that  this  potential  difference  will  be  sufficient  to 

[414] 


PROTECTIVE  APPARATUS 


Sec.  6 


break  down  the  air  gap.  For  an  instant  the  current  flows  from  T 
through  lamps  L,  to  carbon  E,  across  gap  G  to  carbon  E',  through 
solenoid  coil  S  to  R,  through  lamps  L,  to  terminal  T'.  This  condi- 


tion exists  but  for  a  moment,  as  the  current  immediately  energizes 
the  solenoid  S,  causing  core  A  to  be  drawn  up,  carrying  with  it  the 
porcelain  insulator  P  and  contacts  B  and  B',  thus  opening  the  circuit 


[415] 


Sec.  6 


PROTECTIVE  APPARATUS 


containing  the  lamps  N,  N,  etc.,  at  C  and  C'.     A.t  the  same  time  the 

contact  B  makes  contact  with  D,  thus  short  circuiting  the  gap  G. 

Consider  the  break  at  O  as  having  been  repaired.     The  loop  circuit 

is  still  dead  and  can  be  started  by  disconnecting  the  circuit  at  T  T' 


FIG.  251. — Automatic  arc  loop  cutout  switch. 

for  an  instant,  allowing  the  core  A  to  drop,  thus  reconnecting  the 
loop. 

If,  however,  the  circuit  for  any  reason  has  not  been  properly  re- 
paired, or  another  break  has  occurred,  an  arc  will  again  be  established 


FIG.  252.— Non-automatic  oil  switch  3  P.  S.  T.,  100  amperes,  2,200  volts. 

across  gap  G,  the  solenoid  energized  and  the  defective  line  again 
cut  out  in  the  same  manner  as  previously  explained.  This  pro- 
cedure will  continue  until  the  defective  circuit  is  properly  closed. 

[  416] 


PROTECTIVE  APPARATUS 


Sec.  6 


Oil  switches  may  be  sub-divided  into  two  classes: 

1.  Automatic. 

2.  Non-automatic. 

An  automatic  oil  switch  is  an  oil  switch  so  arranged  that  it  will 
disconnect  the  circuit  under  a  predetermined  condition.  Such 
switches  are  seldom  used  on  pole  line  work,  especially  in  systems 
where  the  kv-a.  capacity  of  the  generating  system  is  large,  as  a 
switch  that  would  successfully  open  a  short  circuit  would  be  too 
large  and  expensive.  There  are  many  instances,  however,  where 
space  is  available  and  the  cost  permissible,  in  which  automatic  oil 
switches  may  be  used  to  advantage  to  replace  fuses. 

In  outdoor  substation  installation  where  the  kv-a.  capacity  is 
sufficient  to  warrant  the  cost,  and  protection  from  overload  or  short 


FIG.  253.— Automatic  oil  switch  3  P.  S.  T.,  100  amperes,  2,200  volts. 

circuit  conditions  is  desired,  automatic  oil  switches  are  in  general 
use. 

Figs.  252-254  illustrate  various  types  of  oil  switches  some  of 
which  may  be  made  automatic  or  non-automatic  by  a  slight  change 
in  the  design  of  the  operating  mechanism. 

The  time  switch  (Fig.  255)  is  a  semi-automatic  oil  or  air  break 
switch  in  that  its  operation  may  be  controlled  by  a  time  clock  and  the 
circuits  opened  and  closed  at  predetermined  intervals,  but  is  .non- 
automatic  in  that  its  operation  is  independent  of  any  phenomena 
occurring  in  the  circuit. 

When  it  is  undesirable  to  connect  branch  lines  to  mains  by  fused 
connections  or  automatic  switches,  non-automatic  pole  type  oil 
switches  may  be  used  to  advantage,  as  their  use  facilitates  the  loca- 
tion of  operating  troubles. 

18.  FUSES.  Probably  no  part  of  an  electrical  system  is  subjected 
to  more  severe  conditions  than  is  the  electric  fuse.  Coupled  to  this, 

14  [  417  ] 


Sec.  6  PROTECTIVE  APPARATUS 

is  the  fact,  that  when  once  installed  the  fuse  is  usually  regarded  as 
part  of  the  distribution  or  transmission  circuit  and,  with  the  exception 
of  very  occasional  inspections,  is  given  no  operating  attention. 

The  fuse  installation  therefore  must  not  only  be  able  to  withstand 
all  weather  conditions  and  all  kinds  of  varying  loads,  but  from  its 
very  nature  must  operate  when  occasion  demands  and  open  the 
circuit  satisfactorily. 

On  systems  of  moderate  capacity  the  problem  is  not  serious  as  there 


FIG.  254.— High  voltage  oil  switch  3  P.  S.  T.     Design  ranges  from  100-800  amperes 
and  22,000-110,000  volts. 

is  no  possibility  of  concentrating  a  large  amount  of  energy  in  case  a 
fault  develops  in  the  protected  circuit.  On  larger  systems,  however, 
— those  which  receive  energy  from  a  generating  source  of  relatively 
high  capacity — the  conditions  are  much  more  severe.  Here  the 
fuse  must  be  able  to  operate  under  very  heavy  loads  and  must 
interrupt  without  damage,  a  flow  of  energy  amounting  to  thousands 
of  kilowatts.  The  interruption  of  the  circuit  under  such  conditions 
means  the  very  rapid  dissipation  of  the  consequent  heat,  and  in  its 
effects  this  is  comparable  in  many  cases,  to  a  violent  explosion. 
In  addition,  the  heat  caused  by  the  rapid  expansion  of  the  air  and 

[418] 


PROTECTIVE  APPARATUS 


Sec.  6 


gaseous  metallic  vapors  in  the  electric  arc,  if  allowed  to  continue  for  a 
period  of  more  than  two  or  three  cycles,  is  sufficient  to  destroy  fuse 
holders,  terminals,  etc. 

These  two  conditions,  (a),  the  explosion  effect  at  the  time  of  opera- 
tion, and  (b),  the  fusion  of  terminals,  etc.,  due  to  the  heat  of  the 
electric  arc,  may  be  considered  as  the  most  important  factors  in  the 
design  of  a  satisfactory  fuse. 

Particular  attention  should  be  given  these  points,  and  the  fuse 
construction  which  guards  against  dangerous  rises  in  gaseous  pres- 
sure, and  operates  to  minimize  the  effect  of  heating  is  to  be  recom- 
mended. This  latter  condition  is  secured  by  rapid  extinction  of  the 
arc  formed,  combined  with  ample  heat  radiating  qualities. 

In  the  design  of  terminals,  the  contacts  and  the  insulating  supports, 
particular  attention  must  be  directed  to  the  current-carrying  capaci- 


FIG.  255. — Air  break  3  P.  D.  T.  100  amperes,  220  volt  time  switch. 

ties  and  the  insulation  strength.  When  fuses  are  mounted  in  metallic 
boxes,  exceptional  care  should  be  exercised  that  arcing  from  the 
terminals  to  the  box  is  made  impossible.  When  such  conditions  are 
possible  the  operation  of  the  fuse — particularly  the  open  link  type — 
will  invariably  cause  a  breakdown  and  will  result  in  the  consequent 
destruction  of  the  fuse  installation. 

Proper  contact  area  is  also  of  great  importance  as  a  great  number 
of  fuse  failures  are  due  entirely  to  lack  of  this.  When  the  fuse  clips 
are  light,  and  the  current  density  for  maximum  fuse  rating  is  high, 
the  chances  of  trouble  are  greatly  increased.  When  the  connection  is 
a  knife  blade  contact,  the  removal  and  replacement  of  the  fuse  will 
necessarily  change  the  value  of  the  contact  resistance,  and,  for  this 

[  419  ] 


Sec.  6  PROTECTIVE  APPARATUS 

reason,  particularly  on  heavy  current  circuits,  a  design  of  fuse  holder 
may  be  considered  most  desirable  which  operates  on  a  removable 
hinge  principle. 

Light  contact  clips  which  can  easily  be  bent  or  damaged  by  care- 
less handling  of  the  fuse  holder  should  be  avoided.  One  form  of 
fuse  contact  obviates  this  danger  by  employing  a  special  backing 
post,  which  affords  adequate  protection  to  the  clip  without  impairing 
the  flexibility  of  contact. 

As  the  fuse  is  obviously  the  weakest  part  of  the  electric  circuit,  or, 
at  least  should  be  made  such,  particular  care  is  necessary  to  secure 
conditions,  external  to  the  fusible  strip,  which  shall  be  constant  in 
nature,  or  proper  operating  of  the  circuit  will  be  impaired. 

Proper  fuse  testing  is  necessarily  dependent  on  a  clear  under- 
standing of  fuse  rating.  There  are  no  definite  or  general  rules  cover- 
ing this,  other  than  those  issued  by  the  Board  of  Fire  Underwriters, 
which  may  be  said  to  apply  particularly  to  low  voltage  fuses. 

All  fuses,  because  of  the  principle  upon  which  they  operate,  have 
an  inverse  time  action,  i.e.,  they  will  carry  a  momentary  current  of  a 
much  higher  value  than  that  which  will  cause  them  to  operate,  should 
the  current  be  sustained.  It  is  unreasonable  to  expect  a  fuse  to 
operate  with  the  accuracy  of  a  circuit  breaker.  It  would  seem,  how- 
ever, that  the  method  of  rating  fuses,  as  practiced  by  the  various 
manufacturers,  should  be  clearly  understood  by  operating  companies 
in  order  that  a  properly  selected  protective  device  may  be  installed. 

A  summation  of  the  more  important  points  in  the  general  con- 
sideration of  satisfactory  fuse  operation  may  be  noted  as  follows: 

(1)  The  type  of  fuse,  for  any  given  installation,  should  be  de- 
termined by  a  consideration  of  the  maximum  concentration  of  energy, 
which  is  possible  at  any  protected  point  of  the  distribution  system. 

(2)  The  general  construction  of  the  fuse  should  be  such  that  it 
will  be  able  to  withstand  the  most  severe  climatic  conditions  without 
serious  deterioration. 

(3)  The  current  carrying  parts  should  be  rugged,  self-aligning  and 
of  sufficient  capacity  to  carry  50%  overload  with  a  rise  in  tempera- 
ture not  to  exceed  40°  C. 

(4)  The  design  should  be  such  that  it  will  provide  for  the  removal 
or  the  replacement  of  the  fuse  without  the  possibility  of  accidental 
contact  with  any  live  parts. 

(5)  The  insulation  of  all  current-carrying  parts  and  particularly 
the  insulation  of  the  leading  in  wires,  should  be  such  that  a  breakdown 
between  circuit  and  fuse  box  supports,  or  between  opposite  poles  of 
the  circuit,  after  the  fuse  has  blown,  is  impossible. 

The  principal  forms  of  fuses  used  in  electrical  distribution  are 
covered  by  the  three  following  classifications: 

(1)  Link  Fuses.     (Art.  19.) 

(2)  Enclosed  Cartridge  Fuses.     (Art.  20.) 

(3)  Expulsion  Fuses.     (Art.  21.) 

19.  THE  LINK  FUSE  is  the  simplest  type  and  consists  essentially 
of  a  strip  of  fusible  metal  extended  between  two  terminals  of  a  fuse 

[  420  ] 


PROTECTIVE  APPARATUS 


Sec.  6 


block.  This  fuse  block  or  holder  is  usually  of  porcelain  or  other  suit- 
able insulating  material,  arranged  in  two  parts:  (I)  the  enclosing  body 
with  suitable  arrangement  for  fastening  to  the  fuse  support,  and 
(II)  the  fuse  holder  or  plug  which  is  made  removable  in  order  to 


FIG.  256. — Fuse  holder  for  30  amperes,  2,200  volt  link  fuse. 

allow  the  replacement  or  inspection  of  the  fuse.  Metal  boxes  for 
enclosing  the  fuse  base  and  block  are  employed  in  some  designs. 
Unless,  however,  extreme  care  is  exercised  in  this  construction,  par- 


FIG.  257. — Horn  gap  link  fuse. 

ticularly  relating  to  the  breakdown  distances  from  live  parts  to  the 
metal  box,  this  type  may  prove  unreliable  in  operation. 

The  most  satisfactory  link  type  of  fuse  is  that  in  which  copper 
terminal  clips  form  the  ends  of  the  fuse  strip.     The  use  of  these 

[421  ] 


Sec.  6  PROTECTIVE  APPARATUS 

tends  to  prevent  damage  to  the  fuse  strip  when  it  is  fastened  to  the 
terminal  studs  and  also  insures  a  better  contact.  In  addition  the 
fusible  strip  is  often  provided  with  a  tubular  asbestos  envelope  which 
not  only  protects  the  fuse  while  in  service,  but  tends  towards  its 
more  satisfactory  operation  when  the  fuse  is  melted.  (Figs.  256  and 
257.) 

20.  THE  ENCLOSED  CARTRIDGE  FUSE  consists  of  a  fusible 
strip  encased  in  an  insulating  tube  which  serves  also  as  a  container 
for  an  insulating  substance  which  completely  surrounds  the  fuse  strip. 
The  tube  is  usually  made  of  fibre,  and  the  filling  material  is  com- 
posed of  Calcium  Sulphate  (Plaster  of  Paris)  or  Calcium  Carbonate 
(Whitening),  or  Levigated  Amorphous  Infusorial  Earth,  usually  pow- 
dered or  granular  in  form.  A  combination  of  any  two  or  three,  will 
result  in  a  substance  suitable  as  a  heat  dissipating  material,  but  any 
siliceous  materials  such  as  sand  or  glass  or  any  of  the  porcelain  clays 


FIG.   258. — Enclosed  cartridge  fuse  and  fuse   box.     100  amperes,   2,200  volts. 

are  not  suitable  owing  to  the  ease  with  which  they  may  be  fused  and 
rendered  conducting. 

The  filling  serves  the  three-fold  purpose:  (a)  of  absorbing  the  heat 
liberated  when  the  fuse  is  blown,  (b)  of  condensing  the  vapor  of  the 
molten  metal  and  (c)  of  breaking  the  continuity  of  the  electric 
circuit.  The  ends  of  the  fuse  are  soldered  or  riveted  to  the  metal 
contacts  which  also  serve  to  seal  the  tube,  thus  holding  in  the  filling 
compound. 

When  a  portion  of  the  strip  is  turned  into  vapor  upon  the  opera- 
tion of  an  enclosed  fuse,  pressure  results  and  the  vapor  seeks  to  ex- 
pand through  the  filling  material.  The  hot  gases  pass  over  the  sur- 
faces of  the  minute  particles  which,  on  account  of  their  lower  tem- 
perature, condense  the  gas,  but  when  the  initial  expansion  occurs 
the  air  entrained  between  the  particles  of  filling  material  must  find 
escape.  To  this  end  vents  are  provided  in  the  end  closures  of  the 
cartridge  and  in  order  to  prevent  the  dislodgement  of  the  dust  and 

[422] 


PROTECTIVE  APPARATUS 


Sec.  6 


F  423  ] 


Sec.  6 


PROTECTIVE  APPARATUS 


finer  particles  of  filling,  vent  screens  of  cloth,  canvas,  asbestos  cloth, 
etc.,  are  placed  within  the  ferrules. 

In  some  installations  the  enclosed  type  fuse  has  many  advantages 
over  the  simple  link  fuse.  On  account  of  its  enclosed  construction 
its  general  characteristics  are  more  nearly  uniform  and  therefore  its 
operation  should  be  far  more  definite.  (Fig.  258.) 

In  addition  to  the  standard  type  of  enclosed  fuse,  several  other 
designs  are  found  in  commercial  use;  one  of  which  (Fig.  259),  con- 
sists of  a  glass  tube  containing  a  spiral  spring,  the  lower  end  of 
which  is  connected  to  the  bottom  ferrule.  The  upper  end  of  the 
spring  connects  to  the  fuse  wire,  passing  through  a  cork,  the  upper 
end  of  the  fuse  wire  being  connected  to  a  short  wire  soldered  to  the 
cap  on  the  top  ferrule.  At  the  top  of  the  spiral  spring  and  just 
below  the  cork  is  a  funnel-shaped  liquid  director.  The  glass  tube 
is  filled  with  a  non-inflammable  liquid  of  high  dielectric  strength. 


FIG.  260. — Oscillogram  illustrating  the  action  of  the  fuse  in  FIG.  259  when  opening 
a  short  circuit. 


The  melting  of  the  fuse  wire  releases  the  spiral  spring  which  con- 
tracts instantaneously,  drawing  the  fuse  wire  down  towards  the 
bottom  of  the  tube  and  thus  introducing  a  very  large  gap.  Simul- 
taneously with  the  introduction  of  this  gap,  the  Mquid  extinguishes 
the  arc  and  interrupts  the  current  flow,  the  rapidity  of  its  action 
being  accelerated  by  the  liquid  director  which  is  drawn  down  with 
the  spring  and  so  forces  the  liquid  directly  onto  the  moving  terminal. 

Another  consists  of  a  metal  box  filled  almost  completely  with  oil, 
into  which  the  fusible  strip  is  immersed  except  for  a  small  part  of  its 

[424] 


PROTECTIVE  APPARATUS 


Sec.  6 


length.  (Fig.  261.)  The  portion  exposed  to  the  air  will  melt  first, 
due  to  the  more  rapid  conduction  of  heat  by  the  oil;  when  the  fuse 
blows  an  arc  is  established  above  the  oil  level  and  as  the  metal  fuse 
burns  down  to  the  oil  the  arc  will  be  automatically  extinguished  and 
the  circuit  thereby  interrupted. 


FIG.  261. — Oil  fuse  box  showing  details  of  construction. 

The  oil  fuse  cutout  illustrated  in  Fig.  262  consists  of  an  oil  tank 
in  which  oil  immersed  contacts  are  provided.  A  removable  element 
is  designed  to  carry  the  fuse,  and  a  vent  is  placed  in  the  top  of  this 
element  to  permit  the  escape  of  the  gases  generated  when  the  fuse 
operates. 


FIG.  262. — Oil  fuse  cutout. 

The  removable  element  is  designed  so  that  it  is  necessary  to  insert 
it  completely  and  then  turn  it  before  contact  is  made  with  the 
stationary  contacts  in  the  tank.  This  locks  the  fuse  plug  in  pos- 
ition, thus  protecting  the  operator  from  accidents  which  may  occur 
due  to  refusing  when  a  short  circuit  exists. 

[425] 


Sec.  6  PROTECTIVE  APPARATUS 

Metal  boxes  for  enclosing  and  supporting  the  standard  enclosed 
type  of  fuse  are  very  generally  used.  Since  there  should  be  no 
liberation  of  metallic  gaseous  vapor  when  the  fuse  blows,  which 
vapor  would  tend  to  cause  a  breakdown  between  live  parts  and  the 
metal  case,  no  special  precautions  are  necessary  to  protect  against 
such  conditions. 

Other  materials  of  construction,  such  as  asbestos  lumber  or  im- 
pregnated wood  are  used  and  have  proven  more  or  less  satisfactory. 

21.  THE  EXPULSION  FUSE.  This  type  employs  what  is  essen- 
tially an  open  link  fuse  in  combination  with  a  container  having  in  its 


FIG.  263. — Expulsion  fuse  block  and  box,  100  amperes,  2,500  volts. 

construction  an  explosion  chamber.  This  form  of  design  utilizes 
the  explosive  action  of  the  gases  liberated  when  the  fuse  is  blown, 
directing  these  gases  across  the  arc  in  such  a  way  as  to  extinguish 
it  and  thus  rupture  the  circuit. 

For  overhead  line  service  there  are  two  types  of  expulsion  fuses. 
One  consists  of  two  blocks  of  insulating  material,  between  which  the 
fusible  strip  is  securely  clamped.  (Fig.  263.)  Midway  along  the 
fusible  strip  is  located  an  expulsion  chamber.  Where  the  fuse  strip 
passes  through  this  chamber  its  cross  section  is  reduced,  resulting 
in  a  definite  point  at  which  the  fusing  will  first  take  place.  This 

[426] 


PROTECTIVE  APPARATUS 


Sec.  6 


fusing  point  is  located  directly  back  of  the  discharge  vent  in  the 
holder  and  the  explosion  caused  when  the  fuse  operates  forces  the 
gaseous  vapors  through  the  opening  provided,  thus  extinguishing 
the  arc.  The  melting  of  the  fuse  is  usually  confined  to  the  length 
of  the  fuse  strip  contained  in  the  expulsion  chamber.  In  order  to 
prevent  injury  to  the  block,  at  these  points,  it  is  usual  to  provide 
strips  of  non-inflammable  material  along  the  parts  of  the  fuse  which 
are  directly  in  contact  with  the  fuse  holder.  These  strips  are  made 


FIG.  264. — Expulsion  fuse  for  from 
6,000-22,000  volts. 


FIG.  265. — Expulsion  fuse  for  50 
amperes,  15,000  volts. 


either  of  asbestos  lumber,  of  lignum  vitse  or  of  lava  and  may  be 
readily  replaced  at  a  nominal  cost. 

The  other  form  of  expulsion  fuse  in  general  use  consists  of  a 
tubular  holder  which  serves  as  a  container  for  an  open  link  fuse. 
(Figs.  264  to  267.)  This  holder  is  constructed  of  an  insulating  mater- 
ial, usually  fiber,  which  is  closed  at  one  end  by  a  metal  explosion 
chamber.  The  other  end  of  the  holder  is  left  open  and  provides  an 
exit  for  the  discharging  gases  when  the  fuse  blows.  The  principal 
of  operation  of  this  type  is  identical  to  that  already  described. 

One  other  type  (Fig.  268),  which  is  of  comparatively  recent  de- 

[427] 


Sec.  6 


PROTECTIVE  APPARATUS 


sign,  employs  the  use  of  an  extremely  high  pressure  gas  receptacle 
which  is  connected  to  one  end  of  a  special  form  of  fusible  strip ;  this 
strip  being  connected  in  the  electric  circuit  by  means  of  the  tubular 
arrangement  above  mentioned.  In  its  operation,  this  fuse  melts 
at  a  predetermined  point,  thereby,  releasing  the  gas  from  the  her- 
metically sealed  container.  The  gas  does  not  support  combustion 
and  in  its  discharge  through  the  arc  path  interrupts  the  circuit  by 
violently  blowing  the  metallic  vapor  through  the  open  end  of  the 
tube.  In  addition,  the  rapid  expansion  of  the  gas  cools  the  terminals 
to  very  low  temperatures  and  thus  prevents  the  burning  of  the  metal 
parts. 

Fuse  boxes  similar  to  those  for  enclosed  fuses  are  constructed  of 
wood,  metal  or  asbestos,  or  a  combination  of  asbestos  and  metal. 
The  latter  construction  eliminates  all  metal  except  a  skeleton  frame, 


FIG.  266. — Expulsion  fuse  and  box  for  60  amperes,  2,200  volt  circuits. 

and  provision  is  made  so  that  the  asbestos  board  sides  can  be  readily 
replaced  in  case  of  damage. 

GROUNDING. 

22.  General.  Earth  connections  are  necessarily  made  by  elec- 
trolytic conduction.  To  obtain  low  resistance,  it  is  therefore  neces- 
sary to  have  electrolytic  moisture  in  contact  with  the  earth  plate,  or, 
lacking  thus  a  fair  degree  of  conductivity,  it  is  necessary  to  have  a 
very  large  area  of  cross  section  for  the  current.  There  are  no  dry 
earths  that  are  conductors.  If  the  earth  contains  no  soluble  sub- 
stances which  are  electrical  conductors,  it  is  necessary  to  add  elec- 
trolyte. The  one  precaution  in  choosing  an  electrolyte  is  to  avoid 
one  which  attacks  the  metal  conductors  chemically. 

It  is  impossible  to  make  a  rule  or  practice  to  coyer  all  cases,  but 
investigations  have  shown  that  the  general  practice  of  using  pipe 

[  428  ] 


PROTECTIVE  APPARATUS 


Sec.  6 


earths  can  be  justified  in  nearly  every  case.  Coke,  so  often  recom- 
mended for  earth  connections,  is  not  a  good  conductor  in  itself. 
It  attracts  and  holds  moisture,  but  since  that  moisture  does  not  con- 
tain an  electrolyte  in  solution,  it  leaves  the  earth  connection  with 
high  resistance.  On  the  basis  of  the  first  cost,  and  of  inspection, 
resistance  measurements,  etc.,  the  iron  pipe  earth  is  to  be  recom- 
mended. Iron  is  the  cheapest  available  metal  and  has  thoroughly 
proven  its  serviceability,  even  when  imbedded  in  salty  marshes. 

For  an  electrolyte,  salt  or  washing  soda  is  to  be  recommended. 
In  the  majority  of  conditions,  salt  is  preferable  as  its  resistance  is 
less,  notwithstanding  that  it  has  a  greater  chemical  effect  on  the  iron. 


FIG.  267. — Expulsion  fuse,  60  amperes,  6,600  volts. 

23.  Laws  of  the  Resistance  of  Pipe  Earth  Connections: 

(a)  Resistance  Versus  Depth  of  Pipe. 

The  resistance  varies  approximately  inversely  as  the  depth  in  the 
conducting  stratum. 

(b)  Resistance  Versus  Specific  Resistance  of  the  Earth. 
Practically  all  of  the  resistance  in  the  earth  is  in  the  immediate 

vicinity  of  the  pipe.  This  resistance  depends  on  the  specific  re- 
sistance of  the  material.  The  specific  resistance  depends  upon  the 
amount  of  moisture  and  the  electrolyte  in  the  moisture.  The  lowest 
possible  resistance  obtainable  is  secured  by  pouring  salt  water 
around  the  pipe. 

(c)  Resistance  Versus  Multiple  Pipe  Earths. 

When  it  is  desired  to  lower  the  resistance  to  earth  below  that  of  a 
single  pipe  earth,  drive  others  at  a  distance  of  not  less  than  six  feet 
from  each  other.  Then  the  total  conductance  is  only  slightly  less 
than  the  sum  of  the  individual  conductances,  and  the  total  re- 
sistance is  the  reciprocal  of  the  total  conductance.  For  conditions 

[  429  ] 


Sec.  6 


PROTECTIVE  APPARATUS 


of  uniform  soil,  the  approximate  rules  may  be  stated :  That  two  pipe 
earths  connected  together  give  one-half  the  resistance  of  one,  ten 
pipe  earths  give  one-tenth  the  resistance  of  one,  etc. 

(d)  Resistance  Between  Pipe  Earths  at  Variable  Distances  Apart. 

For  distance  between  pipe  earths  up  to  one  foot  the  resistance  be- 
tween them  increases  rapidly.  For  every  additional  foot,  the  added 
resistance  becomes  less  and  less.  At  a  distance  apart  of  six  feet,  the 
resistance  has  reached  nearly  a  constant  value.  Stated  otherwise, 
the  resistance  between  two  pipe  earths  at  any  distance  apart  greater 
than  six  feet  is  nearly  equal  to  the  sum  of  the  isolated  resistance  of 
each. 


Fio.  268. — Compression  fuse  and  box  for  200  amperes,  2,500  volts. 


(e)  Potential  Distribution  Around  a  Pipe  Earth. 

Since  the  resistance  of  a  pipe  earth  lies  mostly  in  the  immediate 
vicinity  of  the  pipe,  the  greatest  potential  drop  when  the  current 
flows  will  also  be  concentrated  there.  Heating  and  drying  out  will 
tend  to  magnify  this  value. 

(f)  Ampere-hour  Capacity  of  a  Pipe  Earth. 

The  quantity  of  electricity  that  can  be  passed  through  a  pipe 
earth  without  materially  changing  its  resistance,  increases  directly 
with  the  wetness  of  the  earth  in  contact  with  the  iron,  and  the  area 
of  the  iron  surface  exposed  to  the  passage  of  the  current;  and  de- 
creases as  the  resistance  of  the  earth  in  contact  with  the  pipe  in- 
creases. Certain  critical  values  of  current  may  be  carried  con- 
tinuously by  a  pipe  earth  without  varying  the  resistance.  The  higher 
the  current  above  this  critical  value,  the  more  rapid  the  drying  out. 
To  increase  the  ampere-hour  capacity  it  is  necessary  to  keep  the  pipe 
earth  wet  with  salt  water. 

[430] 


PROTECTIVE  APPARATUS  Sec.  6 

(g)  Resistance  of  Pipe  Earth  Versus  Diameter  of  Pipe. 

The  resistance  of  a  pipe  earth  does  not  decrease  in  direct  pro- 
portion to  the  increase  in  the  diameter  of  the  pipe.  Two  pipes 
driven  side  by  side  and  connected  together  will  have  only  a  slightly 
less  resistance  to  earth  than  one  pipe;  a  pipe  two  inches  in  diameter 
has  a  resistance  only  about  six  to  twelve  percent  less  than  that  of  a 
pipe  one  inch  in  diameter. 

(h)  Minimum  Inductance  of  Leads  to  Pipe  Earths. 

The  connecting  wire  between  the  conductor  or  apparatus  to  be 
grounded  and  the  ground  should  be  as  short  as  possible,  by  taking 
as  direct  and  straight  a  path  as  possible. 

Loops  in  the  lead  introduce  unnecessary  impedance  to  high  fre- 
quency impulses. 

The  inductance  of  a  conductor  to  high  frequency  may  be  said  to 
decrease  with  the  increase  of  the  surface  area.  A  hollow  metal  tube 
conducts  as  well  as  a  solid  wire  of  the  same  circumference.  A  flat 
strip  is  an  economical  way  of  getting  large  surface  with  a  small 
weight  of  metal.  The  minimum  degree  of  inductance  with  the 
minimum  weight  of  metal  is  obtained  by  using  separated  parallel 
wires.  Copper  is  best  on  account  of  its  conductivity  and  durability, 
but,  since  only  the  surface  layer  of  metal  carries  the  current,  gal- 
vanized iron  may  be  used  in  some  cases. 

24.  Making  the  Earth  Connection. 

(a)  General.  To  make  the  earth  connection,  take  plain  pieces  of 
standard  one  and  two  inch  pipe  and  drive  them  as  much  over  six 
feet  into  the  ground  as  is  convenient.  Solid  metal  spear  heads  and 
sleeve  joints  on  the  pipe,  which  make  holes  larger  than  the  diameter 
of  the  pipe,  should  not  be  used,  as  the  contact  resistance  is  thereby 
excessively  increased.  If  the  pipe  drives  with  too  much  difficulty,  a 
solid  crowbar  may  first  be  used  to  open  up  the  hole.  If  there  is  no 
stand  available  for  starting  a  pipe  eight  feet  or  more  long,  a  shorter 
pipe,  slightly  larger  in  diameter,  may  be  driven  several  feet  and  then 
withdrawn  to  make  a  start  for  the  longer  pipe. 

After  the  pipe  is  driven  to  place,  a  basin  should  be  scooped  out 
of  the  surface  of  the  earth  around  the  pipe  and  salt  brine  poured  in. 
The  amount  of  salt  water  needed  depends  upon  the  local  conditions 
and  also  upon  the  importance  of  the  ground  connection. 

Where  the  resistance  of  a  pipe  earth  is  less  than  100  ohms  without 
salt,  a  bucket  full  of  brine  may  suffice.  Where  the  pipe  earth  does 
not  reach  moisture  below,  and  the  resistance,  therefore,  is  quite 
high,  several  buckets  of  brine  may  be  necessary.  A  few  handfuls 
of  crystal  salt  should  also  be  placed  around  the  pipe  in  the  basin. 

Whether  the  basin  is  to  be  filled  with  dirt  or  made  permanent  by 
the  use  of  a  tile  with  a  cover,  depends  upon  the  importance  of  the 
earth  connection. 

The  connection  to  the  ground  from  the  system  or  the  apparatus 
to  be  grounded  should  be  made  by  as  direct  a  path  as  possible  and 
with  a  copper  conductor  of  sufficient  area  to  take  care  of  the  maximum 
discharge  which  may  occur  at  that  point.  Angles  and  short  curves 

[431] 


Sec.  6 


PROTECTIVE  APPARATUS 


should  be  reduced  to  a  minimum  and  loops  in  the  connecting  con- 
ductor should  be  carefully  avoided  as  they  introduce  unnecessary 
impedance  to  the  high  frequency  impulses. 

The  connecting  wires  should  be  attached  to  a  pipe  or  pipes  by 
first  making  a  good,  mechanically  strong  connection  and  then  well 


Fia.  269.— Ground  cone. 


FIG.  .270— Ground  box. 


FIG.  271. — Ground  plate. 

soldering  the  joint.  The  point  of  connection  should  be  at  some  point 
on  the  pipe  above  the  deposit  of  salt  in  the  basin  in  order  to  avoid 
any  voltaic  action  between  the  copper  and  iron. 

Ground  wires  should  not  be  run  through  iron  conduits.     If  the 
pipe  earths  are  at  some  distance  from  the  apparatus  to  be  grounded, 

[432] 


PROTECTIVE  APPARATUS  Sec.  6 

the  ground  wire  may  be  run  buried  in  the  earth,  but  such  connection 
should  be  avoided  and  should  be  frequently  inspected  for  possible 
deterioration  of  the  conductor. 

(b)  Earth  Connection  for  A.  C.  Lightning  Arresters.     In  general, 
drive  two  or  three  iron  pipes  into  the  earth  at  a  point  near  the  loca- 
tion of  the  lightning  arrester.    Then  drive  other  pipes  at  a  minimum 
distance  of  six  feet  apart  encircling  the  station  or  pole  structure,  and 
connect  all  of  them  with  a  common  wire.     In  choosing  the  size  of 
conductor  for  the  common  wire  connecting  the  pipe  earths,  con- 
sideration must  be  given  to  the  possible  maximum  discharge  which 
it  may  be  required  to   handle  and    the  size  chosen  accordingly. 
This  common  ground  conductor  should  be  protected  from  possible 
electrolytic  action. 

(c)  Grounding  Secondaries.   When  the  secondaries  of  distribut- 
ing circuits  are  grounded,  the  connection  should  be  made  as  near  the 
transformer  pole  as  possible,  and,  if  it  is  on  the  same  pole  as  a  trans- 
former, it  may  be  connected  to  the  earth  connection  of  the  trans- 
former case,  care  being  taken  that  this  earth  connection  is  sufficiently 
good  for  the  purpose. 

Secondary  ground  connections  should  be  kept  separate  from 
lightning  arrester  grounds  and  should  be  protected  by  a  wood  cover 
extending  from  the  ground  line  to  a  point  seven  feet  above. 

(d)  Grounding    Transformer    Cases.     When    grounding    trans- 
former cases  the  connection  should  be  made  solidly  and  of  sufficient 
size  to  take  care  of  any  possible  breakdown.      Transformers  on  poles 
may  be  grounded  to  one  pipe. 

(e)  Water  Pipe  Grounds.     In  any  system  of  grounding  it  is  ad- 
visable, where  possible,  to  make  a  permanent  connection  to  a  water 
supply  system. 

This  may  be  accomplished  by  fastening  and  soldering  a  pipe  clamp 
securely  to  the  pipe  and  then  soldering  the  ground  wire  to  the  clamp. 
When  a  flat  copper  strap  is  used  for  a  ground  connection  it  may  be 
clamped  securely  to  the  pipe  and  soldered. 

25.  Testing  Grounds.  The  greatest  difficulty  in  making  ground 
connections  is  in  obtaining  reliable  grounds.  When  rigid  and  perma- 
nent connections  can  be  made  to  water  piping  systems,  such  connec- 
tions will  be  found  to  give  the  most  satisfactory  grounds.  It  is 
generally  difficult  to  obtain  such  connections  to  the  water  piping 
system,  except  where  the  ground  is  made  on  a  consumer's  premises 
and  the  consumer  has  also  a  water  service.  In  making  ground  con- 
nections outside,  it  will,  in  practically  all  cases,  be  necessary  to  use 
some  form  of  ground  plate  or  ground  rod.  The  efficiency  of  these 
methods  of  grounding  depends  almost  entirely  on  the  nature  of  the 
soil,  such  grounds,  unless  made  in  permanently  damp  soils,  being 
practically  useless. 

It  is  generally  considered  that  a  ground  is  satisfactory  if  the  re- 
sistance is  less  than  twenty  (20)  ohms.  Therefore,  in  order  to  de- 
termine whether  or  not  satisfactory  grounds  have  been  obtained,  re- 
sistance readings  should  be  made.  In  taking  such  readings,  if  a 

[433] 


Sec.  6  PROTECTIVE  APPARATUS 

water  piping  system  is  available,  so  that  a  test  wire  can  be  attached  to 
a  water  hydrant  or  service  cock,  the  resistance  can  be  measured  be- 
tween the  ground  to  be  tested  and  the  water  piping  system. 
A  convenient  method  of  making  this  test  is  as  follows: 
After  the  ground  has  been  installed  on  the  neutral  wire  of  the 
220- volt  secondary  system,  or  on  one  leg  of  the  110- volt  secondary 
system,  connect  the  ungrounded  leg  of  the  system  through  a  5- 
ampere  fuse  to  an  available  point  on  the  water  piping  system.     If 
sufficient  current  flows  to  blow  this  5-ampere  fuse  the  ground  con- 
nection may  be  considered  satisfactory. 

If  the  ground  wire  is  installed  on  the  neutral  wire  of  a  3-wire, 
440-\olt  secondary  system,  or  on  one  leg  of  a  220- volt  system,  and 
connections  are  made  as  above,  the  current  flowing  should  be  suffi- 
cient to  blow  a  10-ampere  fuse. 


BIBLIOGRAPHY 

A.  I.  E.  E.,  June,  1907.     Steinmetz. 
A.  I.  E.  E.,  June,  1907-12.     Creighton. 
General  Electric  Review,  Feb.,  1913. 
Electric  Bond  &  Share  Co. 
Publications  of  Various  Manufacturers. 


[434] 


SECTION  7 

SYSTEMS   OF   DISTRIBUTION  AND 
TRANSMISSION 

ELECTRICAL  CALCULATIONS 


SECTION  7 
SYSTEMS  OF  DISTRIBUTION  AND  TRANSMISSION 


TABLE  OF  CONTENTS 

ARTICLE 

Introduction 

Description  of  Systems 

Direct  Current 1 

Direct  Current,  Two-Wire  System 2 

The  Edison  Three-Wire  System 3 

The  Direct  Current  Series  Arc  Lighting  System 4 

The  Thury  Direct  Current  Series  System 5 

Alternating  Current 6 

The  Single-Phase  System 7 

The  Single-Phase  Two-Wire  System 8 

The  Single-Phase  Three- Wire  System 9 

The  Two-Phase  System 10 

The  Two-Phase  Three-Wire  System 11 

The  Two-Phase  Four-Wire  System 12 

The  Two-Phase  Five-Wire  System 13 

The  Three-Phase  System 14 

The  Three-Phase  Three-Wire  System 15 

The  Three-Phase  Four-Wire  System 16 

Comparison  of  "Y"  and  "A"  Transformer  Connections..  17 

The  Alternating  Current  Series  System 18 

Comparative    Weight    of    Conductors     Necessary    in   Various 
Systems 19 

Vectors  and  Vector  Diagrams 

General  Discussion 20 

Vector  Addition 21 

Direction  of  Arrows 22 

Single-Phase  Transmission t 23 

Two-Phase  Four- Wire  System 24 

Two-Phase  Three-Wire  System ; 25 

Three-Phase  "Y"  Connected  System. 26 

Three-Phase  "A"  Connected  System 27 

Effect  of  Charging  Current  on  Line  Calculations 28 

Inductance  Formulae 29 

Capacity  Formulae 30 

Methods  of  Calculating  Transmission  Losses 

General 31 

Direct  Current  Two- Wire  System 32 

[437] 


Sec.  7  ELECTRICAL  CALCULATIONS 

ARTICLE 

Two-Wire  Direct  Current  Railway  System 33 

The  Edison  Three-Wire   System 34 

Direct  Current  Series  System 35 

Calculation  of  Alternating  Current  Systems 36 

Explanation  of  the  Line  Loss  Tables 37 

Single-Phase  Two-Wire  System 38 

Single-Phase  Three-Wire  System 39 

Two-Phase  Three-Wire  System 40 

Three-Phase  Transmission 41 

Graphical  Solution  of  a  Three-Phase  Transmission  Line.  .  .  42 

Additions  to  Existing  Systems 43 

Alternating  Current  Series  System 44 

Choice  of  Voltage  on  Transmission  Lines 45 

Corona  and  Corona  Loss 46 

Locating  the  Center  of  Distribution 47 

Transformer  Calculations 

Calculation  of  Transformer  Capacity 48 

Calculation  of  Transformer  Regulation 49 

Calculation  of  Transformer  Efficiency 50 

Voltage  Regulators 

General 51 

Regulation 52 

Single-Phase  System 53 

Two-Phase  System 54 

Three-Phase  Three-Wire  System 55 

Three-Phase  Four-Wire  System 56 

Regulator  Capacity 57 

Resultant  Power-Factors 58 

Power-Factors  of  Various  Types  of  Loads 59 

Economics  of  Transmission 60 

Transpositions 61 

Constant  Voltage  Transmission 62 

Sparking  Distances 63 


438  ] 


INTRODUCTION 

No  attempt  will  be  made  in  this  section  to  cover  the  solution  of 
all  the  electrical  problems  involved  in  the  transmission  of  electrical 
energy.  However,  fundamental  formulae  are  included,  together 
with  definitions  of  the  various  standard  systems  of  distribution, 
and  the  use  of  the  formulae  included  will  enable  the  solution  of 
the  majority  of  electrical  problems  encountered. 

The  tables  have  been  arranged  to  facilitate  the  use  of  a  slide 
rule  and  the  values  contained  are  well  within  its  accuracy. 

DEFINITIONS  OF  TRANSMISSION  AND  DISTRIBUTING 
SYSTEMS. 

1.  Direct  Current  is  unidirectional  current.     It  may  be  constant, 
or  periodically  fluctuating,  as  a  rectified  alternating  current.     A 
continuous  current  is  a  steady  non-pulsating  direct  current.     In 
reality,  the  commonly  so-called  direct  current  systems  more  nearly 
approach  the  definition  of  continuous  current  than  direct  current. 
Therefore,  in  the  following  paragraphs  continuous  and  direct  current 
systems  alike  will  be  termed  Direct  Current  Systems. 

2.  The   Two-Wire  Direct   Current  System   (Fig.   272)   consists 
of  a  two-wire  multiple  circuit  upon  which,  when  used  for  light  and 
power,  is  maintained  a  constant  potential  difference  of   from    110 
to  550  volts.     Such  systems  operated  at  220  volts  have  been  used 
to  a  large  extent  in  isolated  plants.     These,  however,  are  being 
succeeded  by  the  three-wire  direct  or  alternating  current  distributing 
systems.     For  railway  work  (Fig.  273)  a  constant  potential  mul- 
tiple circuit  is  maintained,  using  the  trolley  contact  wire  or  a  third 
rail  as  the  positive  conductor,  and  the  track  rail  as  the  negative 
conductor.     The  track  rail  is  made  the  negative  in  order  that  elec- 
trolytic action,  which  occurs  where  current  leaves  a  conducting 
body,  will  be  confined  to  a  section  close  to  the  power  house.     In 
such  systems  600  volt  circuits  are  the  usual  standard.     However, 
on  interurban  railway  work  600,  750,   1200,   1500  and  2400  volt 
circuits  have  been  used  depending  upon  local  conditions,  such  as 
the  length  of  the  line,  the  volume  of  traffic,  train  schedule,  topog- 
raphy, etc. 

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Fig.  272.  —  D.  C.  two-wire  system. 
f  439  | 


Sec.  7  ELECTRICAL  CALCULATIONS 

3.  The  Edison  Three-Wire  System  is  essentially  two,  two-wire 
systems,  in  which  the  positive  of  one  and  the  negative  of  the  other 
circuit  are  combined  in  one  wire  known  as  the  neutral.  It  is  a 
development  of  the  two- wire  direct  current  system.  Its  use  allows 
the  distribution  of  the  same  amount  of  energy  at  the  same  usable 
voltage  as  that  of  the  two-wire  system  and  at  a  great  saving  in 
copper.  (Double  voltage  being  maintained  between  the  outside 
wires).  The  neutral  wire  carries  only  the  unbalanced  load  of  the 
system.  As  adapted  to  central  station  practice,  it  is  usual  to  connect 
the  wires  in  a  network  (Fig.  274)  and  feeders  are  extended  from  the 
generating  station  to  the  various  load  centers.  It  is  necessary  to 
extend  the  neutral  from  the  station  only  to  points  where  conditions 
of  unbalanced  load  are  known  to  exist.  Because  of  the  small  areas 
covered  by  isolated  plants,  a  system  of  mains  and  branches  is  used 
in  such  installations  instead  of  a  net-work. 

The  difference  of  potential  between  the  outside  wires  of  the 
three- wire  direct  current  system  is  usually  maintained  at  220  volts; 
and  that  between  either  outside  wire  and  the  neutral  is  110  volts. 

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Fig.  273.  —  D.  C.  railway  system. 

4.  The  Direct  Current  Series  Lighting  System  (Fig.  275)  is  one 
in  which  the  current  is  maintained  at  a  constant  value;  the  voltage 
varies  with  the  number  and  characteristics  of  the  lighting  units 
connected.     The  system  consists  essentially  of  a  single  continuous 
conductor  run  from,  and  returning  to,  the  source  of  energy.     In 
this  way  the  area  to  be  served  is  covered,  and  into  the  circuit  are 
connected  in  series  the  arc  or  incandescent  lighting  units.     This 
system  is  usually  confined  to  the  transmission  of  energy  for  street 
lighting. 

5.  The  Thury  Direct  Current  Series  System  is  similar  in  char- 
acter to  the  direct  current  series  lighting  system,  except  that  the 
circuits  are  of  higher  voltage  and  greater  kw.  capacity.     The  source 
of  energy  consists  of  a  number  of  generators  connected  in  series 
by  which  means  high  direct  current  voltages  are  obtained.     This 
is  distinctively  a  system  for  the  distribution  of  energy  for  power  and 
as  such,  is  used  to  some  extent  in  Europe.     The  problem  of  insu- 
lating the  generating  and  the  receiving  apparatus  is  difficult,  because 
of  the  high  voltages  maintained. 

[440] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


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Fig.  274. — Edison  three-wire  system. 

6.  Alternating  Current.  An  alternating  current  or  e.m.f.  is  a 
current  or  e.m.f.  which,  when  plotted  against  time  in  rectangular 
co-ordinates,  consists  of  half  waves  of  equal  area  in  successively 
opposite  directions  from  the  zero  line. 

A  Cycle  is  two  immediately  succeeding  half  waves. 

The  number  of  cycles  per  second  is  known  as  the  frequency. 
Standard  American  frequencies  for  the  distribution  of  energy  for 
light  and  power  are  25  and  60  cycles. 


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Fig.  275. — Direct  current  series  arc  lighting  system. 
[441] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


f  442 


ELECTRICAL  CALCULATIONS  Sec.  7 

7.  Single-Phase  System.     A  term  characterizing  a  simple  alter- 
nating current  circuit  energized  by  a  single  alternating  e.m.f.     Such 
a  circuit  is  usually  supplied  through  two  wires.     The  currents  in 
these  two  wires,  counted  positively  outwards  from  the  source,  differ 
in  phase  by  180  degrees  or  half  a  cycle. 

8.  The    Alternating    Current   Single- Phase   Two-Wire    System 
(Fig.  276)  is  similar  in  circuit  arrangement  to  the  direct  current 
two  wire  system.     When  used  for  the  distribution  of  energy  for  light 
and  power,  it  is  usually  part  of  a  polyphase  system.     For  railway 
installations  potentials  of  11,000  volts  are  in  successful  operation, 
confined  however  to  systems  using  a  trolley  contact  wire.     When 
a  single  phase  system  is  used  for  the  distribution  of  energy  for  light 
and  power,  the  following  secondary  connections  can  be  made: 

Single-phase  two-wire. 
Single-phase  three-wire. 

9.  The  Single-Phase  Three-Wire  System    (Fig.   276)   is  nearly 
always  confined  to  secondary  distribution  and  is  similar  in  circuit 
arrangement  to  the  Edison  Direct  Current  three  wire  system,  es- 
pecially when  interconnected  to  form  a  network.     In  such  a  network 
the  transformer  secondaries  are  connected  at  those  points  to  which, 
in  an  Edison  three-wire  system,  feeders  would  be  extended. 

Main  and  branch  distribution  connected  to  a  single  transformer 
is  more  often  used,  because  of  the  fact  that  failures  in  such  a  system 
confine  themselves  locally,  without  disturbing  a  number  of  con- 
sumers, as  may  occur  in  a  network. 

When  such  a  system  is  used,  it  is  generally  a  part  of  a  polyphase 
primary  distributing  system. 

10.  A  Two-Phase  System  is  one  in  which  the  energy  is  contin- 
uous and  in  which  two  alternating  voltages  are  impressed  upon  the 
receiving  circuit.     The  maximum  values  of  these  two  voltages  are 
90  electrical  degrees  apart  in  time  phase. 

11.  The  Two-Phase  Three-Wire  System  (Fig.  277)  consists  of 
two  single  phase  circuits  (differing  in  phase  by  an  angle  of  90°) 
supplying  energy  over  three  wires,  one  wire  acting  as  the  common 
return  for  both  circuits.     When  the  load  on  such  a  system  is  bal- 
anced, the  current  in  the  common  wire  is  41  percent  greater  than 
that  in  each  outside  wire. 

The  phenomena  of  unbalanced  voltage  and  phase  angle  distortion 
in  this  system  depend  upon  many  variables,  some  of  which  follow: 
the  amount  of  the  load,  the  proportion  of  the  load  on  each  phase, 
the  power-factor  of  the  circuit,  the  voltage,  the  frequency,  the  spacing 
and  diameter  of  conductors  and  the  length  of  line.  (Art.  25). 

The  above  phenomena  may  be  negligible  with  a  low  power-factor 
load  if  the  low  power-factor  load  is  a  small  part  of  the  total  load 
on  a  circuit  having  a  high  power-factor;  and  if  the  conductors  are 
spaced  closed  together,  fairly  long  lines  may  be  used  without  trouble 
from  this  cause. 

The  system  has  been  adopted  to  some  extent  for  the  reason  that 

[443] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


[444] 


ELECTRICAL  CALCULATIONS  Sec.  7 

more  energy  can  be  transmitted  over  the  same  weight  of  conductor 
than  is  possible  in  a  two-phase  four- wire  system.  Against  this,  how- 
ever, must  be  considered  the  necessity  for  higher  insulation,  as  the 
voltage  between  the  outside  phase  wires  is  41  percent  greater  than 
the  single  phase  voltages. 

The  following  secondary  connections  can  be  made  to  such  a  system : 

Single-phase,  two-wire. 

Single-phase,  three-wire. 

Two-phase,  three-wire. 

Two-phase,  four-wire. 

Two-phase,  five-wire. 

Three-phase,  three-wire. 

12.  The  Two-Phase,  Four -Wire  System  (Fig.  278)  differs  from 
the  two-phase,  three  wire  system  in  that  two  independent  single- 
phase  circuits  are  maintained  (differing  in  phase  by  an  angle  of  90°) 
supplying  energy  over  four  wires. 

This  system  is  being  extensively  used  for  power  distribution. 
For  transmission  its  use  is  gradually  giving  way  to  three-phase, 
three-  and  four-wire  systems,  by  the  use  of  which  a  considerable 
saving  in  conductor  material  is  made  possible. 

The  following  secondary  connections  may  be  made  to  a  2-phase 
4- wire  system. 

Single-phase,  two-wire. 

Single-phase,  three-wire. 

Two-phase,  three-wire. 

Two-phase,  four-wire. 

Two-phase,  five-wire. 

Three-phase,  three-wire. 

13.  The  Two-Phase,  Five -Wire  System  (Figs.  277  and  278)  is  a 
two-phase  secondary  system  in  which  the  middle  points  of  the  trans- 
formers in  each  phase  are  connected  together.     From  which  connec- 
tion the  fifth  wire  is  run. 

This  establishes  two  single-phase,  three-wire  systems  with  a 
common  neutral.  Such  a  combination  is  sometimes  used  where 
power  and  light  are  to  be  supplied  from  the  same  transformer  bank. 

14.  A  Three-Phase  System  is  one  in  which  .the  energy  is  con- 
tinuous and  in  which  three  alternating  voltages  are  impressed  upon 
the  receiving  circuit.     The  maximum  values  of  each  of  the  three 
alternating  voltages  occur   120  electrical  degrees    apart    in    time 
phase. 

15.  The  Triree-Phase,  Three -Wire   System   (Fig.  279)   consists 
of  three  single  phase  circuits,  respectively  differing  in  phase  by 
angles  of  120°  and  supplying  energy  over  three  wires. 

In  such  a  system  the  algebraic  sum  of  the  current  in  all  three  wires 
is  zero  at  any  instant,  the  algebraic  sum  of  the  current  in  any  two 
wires  is  equal,  but  opposite  to  that  in  the  thkd  wire.  The  effective 
voltages  between  all  three  wires  are  equal. 

The  system  is  generally  used  for  transmission  work,  for  the  reason 

[445] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


[446] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


[447] 


Sec.  7  ELECTRICAL  CALCULATIONS 

that  from  the  standpoint  of  conductor  material,  it  affords  the  most 
economic  method  for  the  transmission  of  electrical  energy. 

Transformers  at  the  source  of  supply  may  be  connected  either 
Y  or  "A"  without  affecting  the  method  of  connecting  the  trans- 
formers at  the  point  of  energy  consumption  (termed  the  "receiver" 
end). 

Transformers  are  arranged  in  "A"  (Fig.  279)  by  connecting 
three  single  transformers  or  three  coils  of  a  three-phase  transformer, 
in  such  manner  that  a  closed  series  circuit  is  formed. 

The  three  line  wires  of  the  three-phase  system  are  then  tapped 
respectively  to  the  points  at  which  the  transformers  have  been  con- 
nected together. 

Transformers  are  arranged  in  Y  or  star  (Fig.  279)  by  connecting 
together  one  terminal  of  each  of  three  single-phase  transformers 
or  one  wire  of  each  of  the  three  coils  of  a  three-phase  transformer. 
The  three  line  wires  of  the  three-phase  system  are  tapped  one  to 
each  of  the  unconnected  wires  from  each  of  the  three  coils. 

When  connecting  transformers  to  a  three-phase  system,  the  phase 
relations  must  be  maintained  as  illustrated  in  Sec.  6,  Part  1,  Art.  36. 

The  following  secondary  connections  can  be  made  to  a  three- 
phase  three- wire  system: 

Single-phase,  two-wire. 

three- wire. 
Two-phase,     three-wire. 

four- wire. 

five- wire. 
Three-phase,  three-wire. 

four- wire. 

The  connection  "Y"  primary  and  "Y"  secondary  is  seldom 
used,  except  in  a  three-phase,  four-wire  primary  and  secondary 
system;  the  disadvantage  being  that  the  third  harmonic  magnetizing 
current  of  the  transformers  distorts  the  voltage  distribution,  also 
the  neutral  is  unstable,  and  unbalanced  loads  will  force  it  to  shift, 
reducing  the  voltage  on  the  most  heavily  loaded  phase. 

When  a  "A"  secondary  is  used  with  a  "Y"  primary,  the  third 
harmonics  circulate  in  the  closed  "A"  and  preserve  the  voltage 
distribution. 

In  a  three-phase,  four- wire  system,  the  third  harmonic  magnetizing 
current  flows  through  the  neutral  wire  and  the  voltage  distribution 
on  the  transformer  will  be  undisturbed. 

16.  The  Three-Phase,  Four- Wire  System  (Fig.  280)  is  three 
single-phase  circuits,  respectively  differing  in  phase  by  angles  of 
120°  and  supplying  energy  over  four  wires.  In  such  a  system  stan- 
dard voltage  transformers  may  be  connected  in  "Y"  and  the  advan- 
tage of  the  higher  "A"  distributing  voltage  be  obtained.  The 
fourth  wire  is  necessary,  as  it  is  impossible  to  maintain  single-phase 
loads  absolutely  balanced  at  each  point  of  the  distributing  system. 
Unbalancing  wilt  cause  considerable  distortion  in  voltage,  similar 

[448] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


15 


[  449  ] 


Sec.  7  ELECTRICAL  CALCULATIONS 

in  effect  to  the  opening  of  the  neutral  of  an  unbalanced  Edison  three 
wire  system.     The  following  secondary  connections  may  be  made 
to  a  three-phase  four- wire  system: 
Single-phase,  two-wire. 

three- wire. 

Two-phase,     three-wire, 
four- wire, 
five-wire. 

Three-phase,  three-wire, 
four- wire. 

17.  Comparisons  of  the  Relative  Merits  of  "Y"  and  "A"  Trans- 
former Connections. 

(1)  When  transformers  are  connected  in  "A"  a  disabled  trans- 
former may  be  cut  out  and  the  remaining  transformers  will  continue 
to  operate,   in  open   "A"   at  reduced  capacity  without  otherwise 
affecting  the  system.     When  connected  in  "Y,"  one  transformer,  if 
cut  out,  will  completely  disable  the  secondary  system.     It  is  not 
advisable  to  operate  transformers  in  open  "A"  continuously;  for 
under  such  circumstances  unbalanced  electrostatic  conditions  exist, 
wEich  may  cause  high  frequency  disturbances. 

(2)  When  transformers  are  connected  in  "Y"  or  in  accordance 
with  the  "Scott"  method,  the  coils,  or  parts  of  coils  are  in  series 
between  phase  wires,  and,  should  break-downs  occur,  one  trans- 
former may  act  as  a  reactance  in  series  with  line  capacity,  causing 
high  voltage  disturbances.     Such  occurrences  are  confined  to  cases 
in  which  one   transformer  bank  is  used,    and  seldom  occur  when 
two  or  more  transformer  banks  are  connected  in  parallel.     Trans- 
formers connected  in  "A"  are  free  from  such  disturbances. 

(3)  "Y"  connected  systems,  operated  with  a  grounded  neutral, 
limit  the  voltage  which  may  occur  between  the  conductor  and  ground. 
However,  should  a  ground  develop  on  one  phase,  a  short  circuit  will 
result.  When  operating  ungrounded,  a  ground  developing  on  one  phase 
increases  the  potential  between  the  other  two  phases  and  the  ground. 

18.  The  Alternating  Current  Series  System  (Fig.  275)  is  similar  in 
type  to  the  direct  current  series  system  and  its  use  is  generally  con- 
fined to  the  supply  of  energy  for  street  lighting.     It  is  more  flexible 
than  the  direct  current  system,  in  that  transformers  may  be  installed 
which  not  only  protect  the  receiving  apparatus  from  the  high  voltage 
of  the  system,  but  permit  the  use  of  apparatus  requiring  a  current 
value  other  than  that  of  the  main  system. 

19.  COMPARATIVE   WEIGHT   OF    CONDUCTORS   NECES- 
SARY IN  VARIOUS  SYSTEMS. 

The  values  given  in  Table  58  are  based  on  the  following  assump- 
tions: similar  conducting  material,  equal  voltages  at  the  lamps  or 
other  receivers,  equal  amounts  of  power  transmitted,  equal  line 
losses,  unity  power-factor,  and  balanced  conditions.  The  weight 
of  the  conductors  of  a  two-wire  direct  current  system  has  been 
assumed  to  be  100  percent. 

[  450] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


FIG.  281. 


/W™\* 

/00V 

t 

/0™200X 

t 

i  '       ..,                    i       2  PHASE 

2P/fASC 

Ml/      '          9trfn       MII/       *         3WlKE 
f/Ml/                            \       fflfll/ 

41Y/KC 

i                                   _f             i      _                                  //?/?/' 

1 

FIG.  282.                    FIG.  283.                    Fie 

.  284. 

J      t 

_                                /71A' 

t                               **£ 

AS£         "T'                          3PHASC     t&KflM         /f 

5^  3PftA$e 

RC                          jg0%          3W/KC            \  "\"  /OOtf 

\__4WiKC 

/OOK       |                                     -|- 

| 

A/fc/r#AL 

FIG.  285. 


FIG.  286. 


FIG.  287. 


TABLE  58 

COMPARISON  OF  CONDUCTOR  WEIGHTS  FOR 
VARIOUS  SYSTEMS 

System 

Size  of  wire 

Compared 
to  2  Wire 
D.  C. 
Per  Cent. 

Diagram 

2  wire  D.  C  
3  wire  D.  C. 

Neutral  equal  to  outside 
Neutral  one-half  outside 

Neutral  equal  to  outside 

Neutral  one-half  outside 
Common   wire   equal    to 
outside 
Common  wire  1.41  times 
outside 

Neutral  equal  to  outside 
Neutral  one-half  outside 

Neutral  equal  to  outside 
Neutral  one-half  outside 

100.00 
37.50 
31.25 
100.00 

37.50 
.31.25 
75.00 

72.90 
100.00 
31.25 
28.12 

75.00 
33.33 
29.16 

Fig.  281 
Fig.  282 
Fig.  282 
Fig.  281 

Fig.  282 
Fig.  282 
Fig.  283 

Fig.  283 
Fig.  284 
Fig.  285 
Fig.  285 

Fig.  286 
Fig.  287 
Fig.  287 

3  wire  D.  C  

Single  phase  A.  C.  two  wire 
Single   phase  A.  C.    three 

Single   phase  A.   C.  three 
wire 

Two  phase  A.  C.  three  wire 
Two  phase  A.  C.  three  wire 

Two  phase  A.  C.  four  wire 
Two  phase  A.  C.  five  wire 
Two  phase  A.  C.  five  wire 
Three  phase  A.   C.  three 
wire  

Three  phase  A.  C.  four  wire 
Three  phase  A.  C.  four  wire 

20.  VECTORS  AND  VECTOR  DIAGRAMS.  The  solution  of 
many  alternating  current  problems  is  greatly  simplified  by  the  use  of 
vectors.  A  vector  is  a  quantity  which  has  both  magnitude  and 

[  451  J 


Sec.  7 


ELECTRICAL  CALCULATIONS 


direction.  It  may  be  defined  by  giving  its  components  in  the 
direction  of  arbitrarily  chosen  axes  of  reference,  or  by  its  angular 
deviation  from  and  projection  on  some  given  reference  axes.  The 
latter  definition  is  illustrated  in  Fig.  288. 

Draw  the  lines  O'O"  and  e  f  at  right  angles  through  the  point 
O.  Draw  a  line  OA  from  the  point  O  and  consider  it  to  be  rotating 
in  a  counter-clockwise  direction  at  an  angular  velocity  of  «.  6  is 
the  angle  in  radians  between  the  rotating  line  OA  and  the  reference 
line  O'O".  (One  radian  is  an  angle  in  which  the  length  of  the  cir- 
cular arc  and  radius  are  equal.  There  are  2  TT  radians  in  one  cir- 
cumference, therefore,  one  radian  equals  57.295°  and  the  trigono- 
metric functions  apply  to  angles  measured  in  radians  as  well  as  to 
angles  measured  in  degrees.)  At  every  instant  in  its  rotation  there 


FIG.  288. 

is  a  projection  of  the  line  OA  on  e  f  equal  to  OB,  but  OB  equals  AC 
and  AC  =  OA  sin  e.  If  O'O"  is  considered  as  the  instant  of  zero 
time,  and  values  of  6  as  abscissas,  and  corresponding  values  of  OB 
as  ordinates  are  plotted  on  rectangular  co-ordinates,  the  trace  or 
curve  shown  In  Fig.  289  is  produced,  which  is  known  as  the  curve 
of  sines. 

When  there  are  a  number  of  these  curves  formed  by  various  lines, 
all  rotating  at  the  same  velocity,  the  sum  of  all  of  them  at  any 
instant  can  be  obtained  by  considering  the  rotation  stopped  and 
adding  the  lines  one  to  another,  maintaining,  however,  the  angular 
relation  to  O'O"  as  shown  in  Fig.  290.  In  each  case  the  projection 
on  e  f  is  equal  to  the  length  of  the  line  to  be  projected,  times  the 
sine  of  the  angle  between  the  line  and  O'O",  therefore,  the  sum  of 
these  projections  will  be  equal  to  the  projection  of  the  line  N  on 
the  line  e  f. 

Vectors  may  be  applied  to  the  solution  of  alternating  current  prot> 

[452] 


ELECTRICAL  CALCULATIONS 

A 


Sec.  7 


Fig.  289. 

lems  since  the  design  of  alternating  current  machinery  is  such  that  it 
produces  voltage  and  current  waves  which  very  closely  approximate 
the  curve  of  sines,  and  because  the  curve  of  sines  is  the  result  of 
plotting  the  formula  Y  =  A  Sine  X,  which  is  deduced  from  the  vector, 
it  holds  that  the  vector  represents  alternating  current  and  voltage 
variation. 


Sec.  7  ELECTRICAL  CALCULATIONS 

Further,  the  vector  represents  the  maximum  values  of  an  alter- 
nating voltage  or  current  wave,  but  since  the  effective  values  of  sine 
waves — those  values  read  on  voltmeters  and  ammeters — are  related 

to  the  maximum  values  as  follows :  Eeff  = ^=~it  follows  that  the 

A/2 

effective  values  mayjbe  used  directly,  instead  of  multiplying  the 
effective  value  by  v  2  to  obtain  the  maximum  value,  then  applying 
the  resulting  values  to  the  vector  analysis  and  finally  dividing  the 
solution  by  the  V%  to  obtain  the  result  as  an  effective  value. 

21.  Vector  Additions.     Vectors  representing  current  and  vectors 
representing  voltage  cannot  be  added  vectorally,  i.e.,  vectors  repre- 
senting the  same^physical  phenomenon  only  can  be  added  or  sub- 
tracted.    A  vector  representing  a  voltage  generated  in  an  alternator 
winding  may  be  added  to,  or  subtracted  from,  the  vector  representing 
the  voltage  drop  due  to  a  current  flowing  through  a  resistance,  an 
inductance,  or  a  capacity,  but  not  to  the  vector  representing  the 
current  itself. 

In  all  the  following  vector  diagrams  the  vectors  are  considered 
as  that  part  of  the  total  voltages  absorbed  in  resistance,  inductance, 
etc.,  and  not  the  counter  e.m.f.  induced,  because  these  latter  values 
are  180°  out  of  phase  with  the  absorbed  voltage  and  would  need- 
lessly complicate  the  diagrams. 

22.  Direction  of  Arrows.     The  arrow  heads  on  the  ends  of  vectors 
when  taken  in  connection  with  the  angular  deviation  from  the 
reference  axis  of  zero  time,  O'O"  (Fig.  288)  indicate  the  instanta- 
neous direction  of  voltage,  or  the  instantaneous  direction _pf  current 
flow  with  respect  to  an  arbitrarily  chosen  point.* 

The  direction  of  arrows  in  a  vector  diagram  may  be  selected  as 
follows:  Take  any  point  in  the  circuit  and  consider  it  the  reference 
basis;  currents  flowing  away  from  this  point  are  considered  positive, 
and  flowing  towards  it,  negative. 

Voltages  above  this  reference  point  are  positive,  and  below  neg- 
ative. The  arrows  on  the  end  of  the  vectors  are  always  drawn 
furthest  away  from  the  reference  point. 

As  an  example  the  end  of  rib  at  the  dotted  line,  Fig.  293,  is  taken 
as  the  reference  point.  The  arrow  heads  on  all  vectors  must  neces- 
sarily be  away  from  this  point.  If  the  ends  of  «LIa  and  wLIc  had 
been  taken  as  reference  points,  all  the  vectors  would  be  reversed 
but  the  resulting  values  would  be  the  same. 

The  manner  of  choosing,  a  reference  point  is  merely  that  of  locating 
one  that  is  most  convenient  as  the  analysis  depends  upon  the  relative 
and  not  the  actual  location  of  the  various  quantities  in  the  problem. 

23.  Single-Phase  Transmission.     (Fig.  291.)     Draw   the  vector 
E  from  the  origin  O  to  a  scale  proportional  to  the  voltage  at  the 
receiver,  draw  the  vector  I  to  a  scale  proportional  to  the  current 

*By  "direction"  is  meant  the  flow  toward  or  away  from  a  given  point,  and  not 
direction  in  space. 

[454] 


ELECTRICAL  CALCULATIONS  Sec.  7 

at  the  receiver  and  at  an  angle  0°  from  E,  where  6  is  the  angle,  the 
cosine  of  which  is  the  power  factor  of  the  load.  From  the  end  of 
the  vector  E,  and  parallel  to  vector  I,  draw  a  line  rl  to  the  same 
scale  as  E,  rl  being  the  product  of  the  total  resistance  of  both  line 
wires  and  the  load  current.  From  the  end  of  the  line  rl  and  in  phase 
90°  ahead  of  the  line  I  draw  the  line  wLI  to  the  same  scale  as  E; 
toLI  being  the  product  of  the  total  inductive  reactance  of  both  line 
wires  and  the  line  current. 

The  voltage  necessary  to  counteract  the  self-induced  voltage 
of  the  line  wLI  is  drawn  90°  ahead  of  the  line  current  I;  since  the 
voltage  of  self-induction  is  in  time  phase  90°  behind  the  current 
I  producing  it.  The  voltage  necessary  to  counteract  the  voltage 
of  self -inductance  is,  in  time  phase,  180°  from  the  voltage  of  self- 
induction,  therefore,  the  voltage  necessary  to  counteract  the  voltage 
of  self-induction  must  be,  in  time  phase,  90°  ahead  of  I.  By  con- 
necting the  end  of  the  line  wLI,  and  the  origin  O,  the  resultant 


_£_ 

T7' 

Fig.  291. — Single  phase  system 

line  E'  represents  the  voltage  at  the  generator  to  the  scale  of  E. 
The  angle  between  E'  and  I,  6'°,  is  the  angle  of  lag  at  the  generator, 
and  cos.  6'  is  the  power  factor  at  the  generator.  • 

24.  The  Two-Phase  Four- Wire  System  is  calculated  as  two  separ- 
ate single  phase  systems,  since  there  is  no  inter-connection,  and  by 
properly  locating  the  wires  in  reference  to  each  other  (Art.  61) 
mutual  induction  may  be  reduced  to  a  negligible  quantity.  Fig. 
292  illustrates  the  circuits  that  may  replace  the  actual  lines,  using 
concentrated  instead  of  distributed  inductance  and  resistance,  also 
the  vector  analysis  of  this  problem.  All  values  are  obtained  as  in 
Fig.  291,  and  the  vectors  are  marked  with  the  subscript  of  the  phase 
which  they  represent.  Under  balanced  conditions,  the  angles  and 
vector  values  are  the  same  in  both  phases,  therefore,  the  angle 
between  the  resultant  voltages  is  the  same  as  that  between  the  initial 
voltage,  i.e.,  90°,  and  there  is  no  dephasing  action. 

[455] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


25.  In  the  Two-Phase  Three-Wire  System  the  relations  are 
more  complex  since  there  is  a  common  connection  between  phases 
which  carries  a  current  that  lags  in  relation  to  one  phase  and  leads 
in  relation  to  the  other,  thus  disturbing  the  angular  relation  of  the 


A.PHASE 


Cos.  &a 


rlc 


KomMMMA/*- 


C.  PHASE 


Cos.  &c 


Fig.  292. — Two  phase,  four  wire  system. 

resulting  voltages.  As  the  voltages  at  the  generator  have  a  fixed 
90°  relation,  the  solution  is  started  by  first  considering  conditions 
at  the  generator  and  working  toward  the  resulting  conditions  at  the 
receiver. 

[456] 


ELECTRICAL  CALCULATIONS  Sec.  7 

The  accurate  calculation  of  the  voltage  relations  in  a  two-phase, 
three-wire  system  is  difficult. 

The  value  of  the  current  or  power-factor  at  the  generator  cannot 
be  determined  until  the  voltage  at  the  receiver  is  found;  and  the 
voltage  at  the  receiver  cannot  be  determined  until  the  line  drop  and 
dephasing  angle  are  known. 

Again,  the  line  drop  cannot  be  determined  until  the  line  current 
and  powerf actor  are  known;  therefore,  the  line  drop  cannot  be 
determined  until  the  voltage  at  the  receiver  is  known. 

Since  the  line  drop  and  receiver  voltage  are  both  unknown,  it 
is  impossible  to  find  either  without  first  assuming  one,  making  a 
trial  solution  for  the  other  and  so  continuing  until  fairly  accurate 
results  are  obtained. 

By  solving  a  two-phase,  three-wire  line  as  though  it  were  a  two- 
phase,  four-wire  line  and  neglecting  the  dephasing  action  of  the  com- 
mon wire,  a  value  of  voltage  drop  will  be  obtained  which  is  equal 
to  the  average  of  the  accurate  drops.  The  drop  will  generally 
be  greater  in  the  leading  phase  and  less  in  the  lagging  phase. 

The  construction  of  the  vector  diagram  is  illustrated  in  Fig.  293, 
as  follows. 

Draw  E'a  and  E'c  to  a  scale  proportional  to  the  generator  volt- 
ages and  90°  apart.  Draw  Ia  and  Ic  to  a  scale  proportional  to  the 
load  current  and  in  phase  relation  6'°  behind  E'a  and  E'c  where 
cos.  Q'  is  the  powerfactor  at  the  generator. 

Draw  Ib,  the  resultant  of  Ia  and  Ic. 

Draw  wLIa  and  «LIc  to  the  same  scale  as  E'a  and  in  phase 
90°  ahead  of  Ia  and  Ic.  These  vectors  represent  the  voltage  ab- 
sorbed in  the  inductive  reactance  of  the  outside  wires.  Draw  rla 
and  rlc  to  the  same  scale  as  E'a  and  in  phase  with  Ia  and  Ic.  These 
vectors  represent  the  voltages  absorbed  in  the  resistance  of  the  out- 
side wires,  and  are  drawn  from  the  ends  of  the  reactance  drop  vectors, 
Ea  and  Ec  being  the  unknown  quantities;  therefore,  they  must  be 
omitted  in  the  voltages  given  in  the  diagrammatic  sketch  of  the 
line  and  the  drop  in  the  b  or  common  wire  must  be  next  considered. 

From  O  draw  rib  to  the  same  scale  as  E'a  and  in  phase  with  Ib, 
the  current  in  the  common  wire.  This  represents  the  voltage  ab- 
sorbed in  the  resistance  of  the  common  wire.  Draw  wLIb  to  the 
same  scale  as  E'a  and  in  phase  90°  ahead  of  Ib.  This  represents 
the  voltage  absorbed  in  the  inductive  reactance  of  the  b  or  common 
wire.  If  the  line  Ea  is  drawn  from  the  end  of  the  vector  ooLIb  to 
the  end  of  the  vector  rla,  the  A  voltage  at  the  receiver  is  obtained 
both  in  value  and  phase;  likewise  the  line  joining  the  ends  of  the 
vector  ojLIb  and  rlc  represents  the  phase  relation  and  value  of  the 
C  phase  receiver  voltage  EC. 

26.  Three-Phase  "Y"  Connected  System.  (Fig.  294.)  Draw 
Ea,  Eb  and  Ec  from  the  point  O  to  a  scale  proportional  to  the 
receiver  voltages  and  120°  apart.  Draw  Ia,  Ib  and  Ic  from  the 
point  O  to  a  scale  proportional  to  the  receiver  current  and  Qa,  ®b 
and  6C  degrees  from  their  respective  voltages;  0a,  ©b  and  Oc  being 

[457] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


Fig.  293.— Two-phase,  three-wire  system. 


[458] 


ELECTRICAL  CALCULATIONS  Sec.  7 


Fig.  294.— Three-phase  system. 
[459] 


Sec.  7  ELECTRICAL  CALCULATIONS 

the  angles,  the  cosines  of  which  are  equal  to  the  power-factor  of  the 
circuit. 

Draw  rla  parallel  to  Ia  and  to  the  same  scale  as  the  voltage  Ea. 
Draw  coLIa  90°  ahead  of  Ia  and  to  the  same  scale  as  Ea.  The 
line  connecting  O  and  the  end  of  o>LIa  represents  the  voltage  E'a 
at  the  generator.  Eb'  and  Ec'  are  found  in  the  same  manner. 
Lines  connecting  Ea',  Eb'  and  Ec'  represent  the  "A"  voltages. 

27.  In  the  Three  Phase  "A"  Connected  System  (Fig.  294), 
the  line  drop  is  the  same  as  that  in  the  "Y"  connected  system.  If 
the  "A"  voltages  E^a,  EAb  and  EAC,  are  given  it  is  necessary  to 


a 

find  Ea,  Eb,  etc.,  by  the  formula  Ea  =  -^=. 

If  the  current  in  the  single  phase  circuit  of  the  "A"  is  known, 
then  the  line  current  Ia  =  IAE'VO- 

When  these  transformations  have  been  made,  the  vector  diagram, 
Fig.  294,  also  applies  to  the  solution  of  a  "A"  connected  system. 

28.  THE  EFFECT  OF  CHARGING  CURRENT  ON  LINE 
CALCULATIONS.  Charging  current  has  been  neglected  in  the 
above  solutions,  in  order  to  simplify  the  vector  analysis. 

All  polyphase  transmission  lines  may  be  solved  as  single  phase 
lines,  transmitting  half  the  total  amount  of  energy;  (Sec.  7,  Art.  36), 
therefore,  in  correcting  for  charging  current  the  single  phase  system 
only  will  be  considered.  (Fig.  295.) 

Draw  E  to  a  scale  proportional  to  the  receiver  voltage.  Draw  the 
energy  component  of  the  current  I  parallel  to  E  and  to  a  scale  pro- 
portional to  the  energy  component  of  the  load  current;  draw  Im 
in  phase  90°  behind  E  and  equal  to  I  tan.  0,  where  cos.  6  equals 
the  power-factor  of  the  circuit.  I0  is  the  total  current  at  the  re- 
ceiver. Assume  one  half  of  the  capacity  of  the  transmission  line 
concentrated  at  the  receiver  and  one  half  at  the  generator.  Ic 
equals  the  total  charging  current  of  the  line  at  voltage  E.  Subtract 
3/£Ic  from  Im  and  combine  with  I,  which  represents  the  total  current 
corrected  for  charging  current  It. 

Draw  rl  to  a  scale  proportional  to  E,  from  the  end  of  E  and  parallel 
to  I.  This  represents  the  voltage  absorbed,  due  to  the  energy 
component  of  the  load  current  flowing  through  the  total  resistance 
of  the  line. 

Draw  wLI  from  the  end  of  rl  and  in  phase  90°  ahead  of  I.  This 
represents  the  voltage  absorbed  due  to  the  energy  component  of 
the  load  current  flowing  through  the  line  reactance. 

From  the  end  of  &>LI  draw  r(Im-/^Ic)  parallel  to  Im«  This  repre- 
sents the  voltage  absorbed,  due  to  the  difference  between  the  wattless 
component  of  the  load  current  and  one  half  of  the  charging  current, 
flowing  through  the  line  resistance. 

From  the  end  of  r(Im-^Ic)  and  in  phase  90°  ahead  of  (Im-3^Ic) 
draw  o>L(Im-3/2lc),  which  represents  the  voltage  absorbed,  due  to 
the  difference  between  the  wattless  component  of  the  load  current 

[460] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


[461] 


Sec.  7  ELECTRICAL  CALCULATIONS 

and  one  half  of  the  charging  current,  flowing  through    the  line 
reactance. 

A  line  connecting  the  end  of  <oL(Im-^Ic)  and  the  reference  point 
represents  the  voltage  E'  at  the  generator.     A  line  in  phase  90°  ahead 

of  E'  and  equal  to  ^Ic  -=r  combined  with  It  represents  Ig  the  current 

at  the  generator. 

The  formulae  for  solving  the  above  diagram  algebraically  are  as 
follows: 

E    =  voltage  at  receiver. 
E'  =  voltage  at  generator. 
I     =  energy  component  of  load  current. 
Ig    =  current  at  generator. 
Ic    =  charging  current  of  line  at  voltage  E. 
cos.  ©°  =  power-factor  of  load, 
cos.  QI°  =  power-factor  of  generator. 
wL    =  total  reactance  of  line, 
r     =  total  resistance  of  line. 
_  coL  _  x 
r          r 

e'    =  ratio  of  voltage  drop  (due  to  the  energy  component  of 
the  current  flowing  through  the  line  resistance)  to  E. 

e'(a-tan.e+i-) 
Tana= 2L_ 


E'  = 


E  (l+e'+e'atan.e-e'a^j-) 


A=  I  sin.  a  +(tan.9  —  ~-)  cos.  a  —  •—  -=r 
l  21  21    E 

B=|cos.  a  —  (tan. 9  —  -^-)  sin.  al 

tan.  0i=-rr-          cos.  61  =  power-factor  at  generator 
r> 

L       IB 


COB.QI 

These  formulas  are  accurate  for  concentrated  inductance,  re- 
sistance, and  capacity,  but  are  incorrect  for  distributed  inductance, 
resistance  and  capacity. 

When  the  ratio  of  the  charging  current  of  the  line  to  the  energy 
component  of  the  load  current  is  less  than  0.05  the  charging  current 
may  be  neglected.  For  overhead  lines  in  length  up  to  60  miles  at 
25  cycles  and  50  miles  at  60  cycles,  for  potentials  not  exceed- 

[  462  ] 


ELECTRICAL  CALCULATIONS  Sec.  7 

ing  55,000  volts  delivered,  the  error  introduced  by  neglecting 
the  condenser  effect  of  the  line  is  usually  unimportant.  Accu- 
rate formulae  may  be  found  in  the  references  made  a  part  of  this 
section. 

The  increase  in  voltage  at  no  load  due  to  the  charging  current  of 
the  line  flowing  through  the  reactance  may  be  found  by  using  the 
following  formula. 

e  =  voltage  rise  in  per  cent. 
1  =  length  of  line  in  miles, 
f  =  frequency  in  cycles  per  second. 
_  57  I2  f2 
109 

20.  FORMULAE  FOR  INDUCTANCE  OF  NON-MAGNETIC 
WIRES. 

Symbols: 

d  =  distance  between  wires  in  inches. 

r   =  radius  of  conductor  in  inches. 

h  =  distance  between  wire  and  ground,  in  feet. 

L  =  inductance  in  millihenries. 

f    =  frequency  in  cycles  per  second. 

x  =  reactance  in  ohms. 

Inductance  of  Single  Conductor  When  Using  the  Ground  as  a 
Return  Circuit. 

L  =  0. 1408  flogxo— ")  +0.0152  millihenries  per  1000  feet  of 
V  r  J  conductor. 

x    =     v        ohms  per  1000  feet  of  line. 

Inductance  of  Two  Parallel  Line  Wires. 

L   =0.2816  ( logio  —^+0.0305  millihenries  per  1000  feet  of 
\          *  J  line  (2000  ft.  of  wire.) 

x    =  — —  ohms  per  1000  feet  of  line. 


30.  FORMULAE  FOR  CAPACITY. 

Symbols : 

r    =  radius  of  wire  in  inches. 
d   =  distances  between  wires  in  inches, 
h   =  height  of  wire  above  ground  in  feet. 
C  =  capacity  of  wires  in  microfarads. 
Ic  =  charging  current  in  amperes. 
[463] 


See.  7  ELECTRICAL  CALCULATIONS 

f    =  frequency  in  cycles  per  second. 

E  =  effective  voltage  between  lines  or  voltage  between  line  and 
•  ground. 

Capacity  of  One  Conductor  to  Ground. 

C  =  —          -r  microfarads  per  1000  ft.  of  conductor. 

m  ^~Ell 

logic  — 

Ic  ==  — ~^Tr$ —  m  amperes  per  1000  ft.  of  line  wire. 
E  =  voltage  between  wire  and  ground. 
Capacity  Between  Two  Parallel  Conductors. 

C  =°-QQ3677  microfarads  per  1000  ft.  of  line  (2000  ft.  of  con- 
log!,)  —  ductor). 

c\     f  r~*  "p1 

Ic  =  r^ — -  amperes  per  1000  ft.  of  line. 

E  =  voltage  between  wires. 

31.  METHODS  OF  CALCULATING  TRANSMISSION  LOSSES. 

The  calculations  of  practical  transmission  problems  may  be  divided 
into  three  general  classes: 

(a)  Load,  length  of  line,  voltage,  and  size  of  wire  given.     Find 
voltage  drop  and  power  loss. 

(b)  Load,   voltage,  length  of  line,  and  per  cent  voltage  drop 
or  power  loss  given.     Find  size  of  wire  required. 

(c)  Size  wire,  voltage,  length  of  line  and  per  cent  voltage  drop 
or  power  loss  given.     Find  possible  load. 

32.  Direct  Current  Two- Wire  System. 
Symbols : 

r    =  resistance  in  ohms  per  1000  ft.  of  wire. 

1    =  length  of  line  in  feet. 

W  =  load  in  kilo  watts. 

E  =  voltage  between  wires  at  load. 

e    =  per  cent  voltage  drop. 

?=  per  cent  power 
=  load  current. 

Formulae : 

WXIOOO 
~E~ 

2rll 
e=p  = 


10  E 

f  464] 


ELECTRICAL  CALCULATIONS  Sec.  7 

(I)  Problem. 

Determine  the  percentage  power  loss  and  voltage  drop  when 
100  kilowatts  are  transmitted  a  distance  of  1000  feet  at  220  volts 
using  500,000  cir.  mils  copper  cable  with  weatherproof  insulation. 

r    from  Sec.  3  =  0.02116. 

100X1000 
I  = 220 =  °    amperes. 

2  X  0.02116  X  1000  X  454 

P=e=  10  X  220    '  =8'74%- 

„  ..  eE       8.74  X  220 

Volts  drop=-^-= JQQ =  19.21  volts. 

pW       8.74  X  100 

Power  1088=-^-  = =7^ =8.74  kilowatts. 

1UU  iOO 

The  current,  454  amperes,  is  within  the  specified  current  carrying 
capacity  of  500,000  cir.  mil.  Triple  Braid  Weatherproof  Copper 
Wire. 

(II)  Problem: 

Determine  the  size  copper  conductor  necessary  to  transmit  100 
kilowatts  a  distance  of  500  feet  at  220  volts,  allowing  5%  voltage 
drop. 

Formulae : 

W  X  1000 


211 
100X1000 

220 
5  X  220  X  10 


454  amperes. 
=  0.0242  ohm. 


2  X  500  X  454 

From  Sec.  3  the  size  copper  wire  having  a  resistance  of  0.0242 
ohm  per  1000  ft.  will  be  found  to  be  450,000  cir.  mils  (nearest  size). 
The  current,  454  amperes,  is  within  the  specified  current  carrying 
capacity'of  450,000  cir.  mils.  Triple  Braid  Weatherproof  Copper  Wire. 

(Ill)  Problem: 

Determine  the  power  that  can  be  transmitted  a  distance  of  500 
feet  at  220  volts,  using  0000  solid  copper  wire.  Assume  a  power 
loss  of  10%. 

[  465  ] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


Formulae: 


10 


2rl          2rl 
El 
~  1000 

From  Table  35  in  Sec.  3,  find  r 
10  X  220  X  10 


I 


0.04893. 
=  450  amperes. 


2  X  0.04893  X  500 

This  exceeds  the  current  carrying  capacity  of  No.  0000  Triple  Braid 
Weatherproof  wire,  which  is  325  amperes.  Therefore  the  maximum 
load  that  can  be  transmitted  is: 


W  = 


325  X  220 
1000 


=  71.5  kilowatts. 


33.  Two- Wire  Direct  Current  Railway  System.  These  calcu- 
lations are  the  same  as  for  the  two-wire  Direct  Current  System  when 
there  is  a  negative  and  positive  feeder  from  the  station  to  the  load. 
When  connections  are  made  as  in  Fig.  296,  the  resistance  of  the  trolley 
wire  and  rails  must  also  be  considered. 


F/reoe* 


Fig.  296. 

Symbols: 

r0  =  resistance  in  ohms  per  1000  ft.  of  trolley  wire. 

r    =  resistance  in  ohms  per  1000  ft.  of  feeder  wire. 

ri  =  resistance  in  ohms  per  1000  ft.  of  rails  and  bonds. 

1    =  length  of  line  in  feet. 

W  =  load  in  kilowatts. 

E  =  voltage  between  trolley  wire  and  rails  at  load,  j 

e    =  per  cent  voltage  drop. 

p  =  per  cent  power  loss. 

I    =  load  current. 

I0  =  current  carried  by  feeder. 

(I)  Problem: 

Determine  the  per  cent  power  loss,  in  transmitting  90  kilowatts  a 
distance  of  5000  feet  at  600  volts,  assuming  a  250,000  cir.  mils  cop- 

[  466  ] 


ELECTRICAL  CALCULATIONS  Sec.  7 

per  Triple  Braid  Weatherproof  feeder  cable,  a  No.  0000  copper  trolley 
wire,  a  single  track,  composed  of  80  Ib.  rails  bonded  with  2-20" 
No.  0000  copper  rail  bonds. 

Formulae  : 

n  =  total  resistance  per  1000  ft.  of  line. 


T_WX  1000 

E 

_R1I 

~P~IO~E 

T  -( 


r 
See  Sec.  3  for  resistances. 

r  =  0.04233  ohm,  r0  =  0.04893  ohm/n  =  0.007746  ohm. 


,     90X1000     1KA 

I  =  - — —— —  =  150  amperes. 

0.030376  X  5000  X  150 
P=  10X600  ~3-8%- 

T       0.030376-0.007746  w  1  _A      QA  . 

Io= OQ4233        -  X  150=  80.4  amperes. 

This  current  is  very  much  below  the  allowable  current  carrying 
capacity  of  the  conductors  considered. 

(II)  Problem: 

Determine  the  size  feeder  necessary  to  transmit  90  kilowatts 
10,000  feet  at  600  volts,  assuming  No.  0000  copper  trolley  wire,  a 
single  track  of  80  Ib.  rails,  bonded  with  2-20"  No.  0000  copper  bonds. 
The  voltage  loss  assumed  to  be  10%. 

Formulae : 
I  =  WX1000 

pE  10  _  eE  10 
~TT~  ~TT~ 
(R— rO  TO 


[467] 


Sec.  7  ELECTRICAL  CALCULATIONS 

e  =  10%. 

,       90  X  1000 

— gOQ =150  amperes. 

w      10X600X10 

R=  107000X150  =ao4  ohms- 

(0.04-0.007746)0.04893  _nnQ,, 
r-p  — u.uy-±o. 


0.04893  +0.007746  -  0.04 
Size  feeder  from  Sec.  3  is  No.  0  solid. 

Io=    0.048°93+OX)9811X15()  =  50 

(III)  Problem: 

A  railway  has  been  transmitting  50  kilowatts  at  600  volts  over 
a  300,000  cir.  mil.  copper  feeder  connected  to  a  No.  0000  copper  trolley 
wire.  The  distance  of  transmission  is  20,000  ft.  The  single  track 
consists  of  80  Ib.  rails,  bonded  with  2-20"  No.  0000  copper  bonds. 
Find  the  energy  that  can  be  transmitted  at  1,200  volts,  allowing 
10%  power  loss. 

•          r  r° 


T    =  eE  1Q  =  PE  10 
Rl      =    Rl 


= 

1000 
See  Sec.  3  for  resistances. 

r    =  0.03531  ohm,  r0  =  0.04893  ohm,  rx  =  0.007746  ohm. 


10X1200X10 


.028226-0.007746^0100 
Io  =  -    —  0"6353T~   ~X212-2  =  123-2  amperes. 

The  value  is  well  within  the  carrying  capacity  of  the  cable. 
„,      1,200X212.2     <-,__,., 

w=      1,000     =255  blowatts- 

The  more  complex  problems  covering  net-works  will  not  be 
given,  A  general  solution  for  such  problems  is  of  little  value  because 
of  the  multiplicity  of  variable  conditions  prevailing. 

[  468  ] 


ELECTRICAL  CALCULATIONS  Sec.  7 

34.  The  Edison  Three-Wire  System.     The  calculation  for  feeders 
in  this  system  is  similar  to  that  of  the  two-wire  system.     The  voltage 
used  is  that  between  the  two  outside  wires  and  not  the  voltage  be- 
tween the  outside  and  neutral  wire.     Two  wire  taps  from  a  three- 
wire  system  are  also  calculated  in  the  same  manner.     The  voltage 
used  depending  upon  whether  the  tap  is  made  between  the  outside 
and  neutral  or  between  the  two  outside  wires.     In  the  former  case 
the  voltage  between  the  outside  and  neutral  wire,  and  in  the  latter 
the  voltage  between  the  outside  wires  is  used. 

35.  Direct  Current  Series  System. 
Symbols: 

r     =  resistance  in  ohms  per  1000  feet  of  wire. 

I     =  current  of  lamps. 

E    =  voltage  of  lamps. 

E'  =  machine  voltage. 

1     =  length  of  line  in  feet. 

N  =  number  of  lamps. 

Problem: 

Find  the  voltage  at  the  generator  when  No.  6  copper  wire  is  used 
to  transmit  energy  for  50  —  4  ampere  lamps,  each  consuming  80  volts; 
the  total  length  of  line  being  20,000  feet. 

Formulae  : 


The  resistance  of  No.  6  copper  wire=  0.3944  ohm.     (See  Sec. 
No.  3.) 

E,=0.3944 


E'  =  4,03  1.55  volts. 

It  will  be  noted  that  the  voltage  drop  is  such  a  small  part  of  the 
total  voltage  that  the  calculation  depends  upon  the  number  of  lamps, 
rather  than  the  length  of  the  line.  A  line  40,000"  ft.  long  will  have 
a  voltage  drop  of  31.55X2=  63.10  volts  =  1.555%  drop. 

36.  CALCULATION  OF  ALTERNATING  CURRENT  SYS- 
TEMS. Before  making  any  calculation  the  relations  that  the  vari- 
ous systems  bear  to  each  other  should  be  known.  The  following 
short  discussion  is  based  upon  an  equal  size  wire  in  each  leg  of  the 
transmission  line  and  an  equal  voltage  between  phase  wires: 

I0  =  load  current. 

r    =  resistance  of  one  wire. 

W  =  power  transmitted  in  watts. 

[469] 


Sec.  7  ELECTRICAL  CALCULATIONS 

E  =  effective  voltage  between  wires, 
cos.  6  =  power-factor  of  load. 

p   =  ratio  of  power  loss  to  power  delivered. 

Determine  the  per  cent  power  loss  for,  single-phase,  two-phase 
four- wire;  two-phase  three- wire,  and  three-phase  three- wire  systems. 

Single-phase : 
W 


Po 


'E  cos.  8 
W2 


"E2  cos.2  0 
Power  loss  in  one  wire  is 

rP-  2 

'- 


Total  power  loss  is 
2r  W2 


The  ratio  of  power  loss  (p)  to  load  is 

_  2rP0_      2rW2 
W    ~WE2cos.20 

2rW 


P~ 


E2  cos.2 


Two-phase,  four- wire: 

W 
"   2Ecos.  e 

T2=         W2 

4  E2  cos.2  6 

Loss  in  one  wire 
rP0  = 


4  E2  cos.2  6 
Loss  in  four  wires 

4rW2  rW2 


0  ~ 


4  E2  cos.2  6  ~  E2  cos.2  6 
_  4  r  PQ  _        rW2  r  W 

W     ~W  E2  cos.2  6  ~  E2  cos.2  0 

F  470  ] 


ELECTRICAL  CALCULATIONS  Sec.  7 

Two-phase,  three-wire: 

la 


4  E2  cos.2  9 
Ib  =IaV2 


4E2cos.29     2E2cos.29 

Total  loss 

rW2  rW2  rW2  r  W2 

rI2a+rI2b+rI2c  = ,  m_  ,Q+TI?,  ^  ,  Q+ 


4E2cos.26  '  2  E2cos.2  6  '  4E2cos.29    E2  cos.2  9 
_  Total  loss_        r  W2  r  W 

W        ~WE2  cos.2  9  ~E2  cos.2  9 

Three-phase,  three-wire: 
W 


V3  E  cos.9 

W2 
I2°=3E2cos.29 

Loss  in  one  wire 
rW2 


rP0  =; 


"3  E2  cos.2  0 
Loss  in  three  wires. 
3rW2 


3rl2 


3  E2  cos.2.  6 
_3rI2_        rW2  rW 

p      W    ~WE2cos.20    E2cos.20 

Summary : 

Single-phase  P  =  E2Vos^9 

rW 

Two-phase,  4-wire    P=E2cos2e 

r  W 

Two-phase,  3-wire    P=E2coSt2e 

r  W 
Three-phase,  3-wire  P  =  E2cos2e 

Thus  it  follows,  that  with  the  same  size  wires  and  equal  voltage 
between  wires,  the  per  cent  power  loss  is  the  same  hi  the  two-phase 
four-wire;  two-phase  three-wire;  and  three-phase  three-wire 

[471] 


Sec.  7  ELECTRICAL  CALCULATIONS 

systems,  and  in  all  these  systems  it  is  only  one-half  of  that  of  a 
single-phase  system. 

Therefore,  by  considering  one-half  the  load  and  solving  as  a 
single-phase  two-wire  line,  the  correct  results  will  be  obtained  for 
each  of  the  three  systems  mentioned.  This  also  holds  true  for 
per  cent  voltage  drop,  with  the  exception  of  the  two-phase  three- 
wire  system,  in  which  the  average  voltage  and  not  the  actual  voltage 
drop  will  be  obtained  because  of  the  dephasing  action  of  the  common 
wire. 

37.  EXPLANATION  OF  THE  LINE  LOSS  TABLES. 
Symbols : 

r    =  resistance  in  ohms  per  1,000  ft.  of  wire. 

—  =  ratio  of  reactance  to  resistance, 
r, 

1    =  length  of  the  line  in  feet. 
W  =  load  in  kw. 

E  =  voltage  between  wires  at  the  receiving  end  of  the  line, 
p   =  power  loss  in  per  cent  of  energy  at  the  receiving  end  of 

the  line. 

e    =  total  voltage  drop  in  per  cent  of  the  receiver  voltage, 
e'  =  voltage  drop  due  to  the  energy  component  of  the  load 

current  flowing  through  "the  line  resistance,  in  per  cent 

of  the  receiver  voltage. 
I    =  energy  component  of  the  load  current. 
Io  =  total  load  current. 

Ic  =  total  charging  current  of  the  line  at  voltage  E. 
a   =  voltage  drop  factor,  Table  61,  Sec.  7. 
b   =  power  loss  factor,  Table  59,  Sec.  7. 
q   =  ratio  of  the  total  current  to  the  energy  component  of  the 

current,  Table  62,  Sec.  7. 

Formulae: 
Single  phase: 

WX1000 


I    = 


e'  = 


E 

2rll 
10  E 


e    ="' 


e'b 
Io  =ql 

Polyphase:' 

WX1000 


I   = 

e'  = 


2E 
2rll 
10  E 

F  472  1 


ELECTRICAL  CALCULATIONS  Sec.  7 

e    =e'a 
p   =e'b 

I0  =  q  I 

The  charging  current  of  the  line,  Ic  is  found  by  obtaining  the 
value  of  I,*,  from  the  Tables  in  Sec.  3,  for  the  proper  size  of  conductor 
and  the  separation  of  the  conductors  in  feet;  per  thousand  feet  of 
line,  per  thousand  volts  between  wires. 

Then 


Ic 


locEl 


108 

The  energy  component  of  the  current  I  and  the  per  cent  voltage 
drop  due  to  this  energy  component  of  the  current  flowing  through 
the  line  resistance,  may  be  found  from  the  formula  given  above. 

Divide  Ic  by  I.  Apply  this  ratio  to  Table  59  in  conjunction 
with  the  power-factor  of  the  load,  and  find  the  value  of  b. 

Multiply  e'  by  b,  securing  the  power  loss  in  per  cent. 

To  find  the  correct  power-factor  at  the  receiving  end  of  the  line, 
apply  the  power  loss  factor  b  to  the  Power-factor,  Conversion  Table 
60,  Sec.  7.  This  power-factor  is  used  in  conjunction  with  Table  61, 
Sec.  7,  to  calculate  the  a-c.  voltage  drop.  Find  the  ratio  of  the 

inductive  reactance  to  ohmic  resistance  -  for  the  size,  spacing  and 

material  of  the  conductor  from  the  reactance  and  resistance  tables 
in  Sec.  3. 

With  this  value  of  —  and  the  corrected  power-factor,  find  values 

of  a  from  Table  61,  Sec.  7.  These  values  multiplied  by  e'  will  give 
the  per  cent  voltage  drop.  To  find  the  generator  power-factor, 
divide  (100  +p)  by  (100  +e);  and  multiply  by  the  corrected  power- 
factor.  This  will  give  the  uncorrected  power-factor  at  the  generator 

end.    Multiply  -y-  by  (100+e)2,  divided  by  (100+p),  thus  obtain- 

ing the  corrected  values  for  ratio  of  charging  current  to  the  energy 
component  of  the  current.  Apply  these  values  to  Table  59  as  before, 
and  the  resultant  value  of  b  when  applied  to  Table  60  will  give  the 
correct  power-factor  at  the  generating  end  of  the  line.  The  for- 
mulae for  this  are  as  follows: 


K  Ic       (100  +e)2 

I  I  A   (100+p) 

The  values  in  Table  62  for  the  power-factor  and  for  the  various 
systems  give  a  constant  q  by  which  the  energy  component  I  may 
be  multiplied,  obtaining  the  actual  load  current  flowing  in  the  wire. 

NOTE:  All  tables  in  this  section  may  be  interpolated  in  a  manner 
similar  to  that  used  in  the  interpolation  of  logarithmic  tables. 

f  473  ] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


TABLE  59 

POWER  LOSS,  VALUES  OF  "b» 

Ic 
I 

P.F. 

0.0 

0.1 

0.2 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

0.9 

1.0 

.40 
.45 
.50 
.55 

6.25 
4.94 
4.00 
3.31 

6.02 
4.74 
3.83 
3.16 

5.80 
4.55 
3.66 
3.01 

5.59 
4.37 
3.50 
2.87 

5.37 
4.19 
3.35 
2.74 

5.17 
4.01 
3.20 
2.61 

4.97 
3.84 
3.05 
2.49 

4.77 
3.67 
2.91 
2.37 

4.58 
3.51 
2.77 
2.25 

4.39 
3.36 
2.64 
2.14 

4.21 
3.20 
2.52 
2.04 

.60 
.65 
.70 
.75 

2.78 
2.37 
2.04 
1.78 

2.65 
2.25 
1.94 
1.69 

2.52 
2.14 
1.85 
1.61 

2.40 
2.04 
1.76 
1.54 

2.28 
1.94 
1.67 
1.47 

2.17 
1.85 
1.59 
1.40 

2.07 
1.76 
1.52 
1.34 

1.97 
1.67 
1.45 
1.28 

1.87 
1.59 
1.39 
1.23 

1.78 
1.52 
1.33 
1.19 

1.69 
1.45 
1.27 
1.15 

.80 
.85 
.90 

1.56 
1.38 
1.23 

1.49 
1.33 
1.19 

1.42 
1.27 
1.15 

1.36 
1.22 
1.11 

1.30 
1.18 
1.08 

1.25 
1.14 
1.06 

1.20 
1.10 
1.03 

1.16 
1.07 
1.02 

1.12 
1.05 
1.01 

1.09 
1.03 
1.00 

1.06 
1.01 
1.00 

.95 

1.11 

1.08 

1.05 

1.03 

1.02 

1.01 

1.00 

1.00 

1.00 

1.01 

1.03 

.98 

1.04 

1.02 

1.01 

1.00 

1.00 

1.00 

1.01 

1.02 

1.04 

1.06 

1.09 

.99 

1.02 

1.01 

1.00 

1.00 

1.00 

1.01 

1.03 

1.04 

1.07 

1.10 

1.13 

1.00 

1.00 

1.00 

1.01 

1.02 

1.04 

1.06 

1.09 

1.12 

1.16 

1.20 

1.25 

.99 
.98 
.95 
.90 

1.02 
1.04 
1.11 
1.23 

1.04 
1.06 
1.14 
1.29 

1.06 
1.09 
1.18 
1.34 

1.09 
1.13 
1.23 
1.40 

1.12 
1.16 
1.28 
1.47 

1.15 
1.21 
1.33 
1.54 

1.20 
1.25 
1.39 
1.62 

1.24 
1.31 
1.46 
1.70 

1.29 
1.36 
1.53 
1.78 

1.35 
1.43 
1.61 
1.87 

1.41 
1.49 
1.69 
1.97 

.85 
.80 
.75 
.70 

1.38 
1.56 
1.78 
2.04 

1.45 
1.64 
1.87 
2.15 

1.52 
1.72 
1.96 
2.26 

1.59 
1.81 
2.07 
2.37 

1.67 
1.90 
2.17 
2.49 

1.76 
2.00 
2.28 
2.61 

1.85 
2.10 
2.40 
2.74 

1.94 
2.21 
2.52 
2.88 

2.04 
2.32 
2.64 
3.02 

2.14 
2.44 
2.77 
3.16 

2.25 
2.56 
2.91 
3.41 

NOTE:  Values  below  heavy  lines  are  for  leading  power-factors. 

38.  Single-Phase  Two-Wire  System. 

Problem: 

Find  the  power  loss  in  kw.  and  the  voltage  drop  in  volts,  when 
transmitting  50  kw.  at  220  volts,  80%  power-factor,  on  a  single 
phase  60  cycle  line  200  feet  long,  using  No.  0000  stranded  copper 
T.  B.  W.  wire,  spacing  between  wires  12  inches. 


I  = 


50X1000 
220 


=  227  amperes. 


From  Table  36,  Sec.  3,  r=  0.04997. 
2X0.04997X200X227 


e  = 


10X220 


2.06 

[474] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


TABLE  60 

CONVERSION  TABLE 

To  find  power-factor  from  power  loss  table.' 

P.F. 

b 

P.F. 

b 

P.F. 

b 

P.F. 

b 

1.00 

1.000 

0.80 

1.562 

0.60 

2.780 

0.40 

6.250 

0.99 

1.020 

0.79 

1.602 

0.59 

2.872 

0.98 

1.041 

0.78 

1.643 

0.58 

2.972 

0.97 

1.063 

0.77 

1.686 

0.57 

3.077 

0.96 

1.085 

0.76 

1.731 

0.56 

3.187 

•• 

0.95 

1.108 

0.75 

1.777 

0.55 

3.305 

0.94 

1.131 

0.74 

1.826 

0.54 

3.429 

0.93 

1.156 

0.73 

1.876 

0.53 

3.567 

0.92 

1.181 

0.72 

1.930 

0.52 

3.698 

t 

0.91 

1.207 

0.71 

1.977 

0.51 

3.844 

• 

0.90 

1.234 

0.70 

2.041 

0.50 

4.000 

. 

0.89 

1.262 

0.69 

2.100 

0.49 

4.164 

0.88 

1.291 

0.68 

2.162 

0.48 

4.340 

, 

0.87 

1.321 

0.67 

2.227 

0.47 

4.526 

0.86 

1.352 

0.66 

2.295 

0.46 

4.725 

0.85 

1.384 

0.65 

2.367 

0.45 

4.939 

mt 

0.84 

1.417 

0.64 

2.441 

0.44 

5.165 

0.83 

1.450 

0.63 

2.512 

0.43 

5.408 

0.82 

1.487 

0.62 

2.601 

0.42 

5.668 

0.81 

1.524 

0.61 

2.687 

0.41 

5.948 

From  Table  45,  Sec.  3,  x,  for  60  cycles  =  0.0953 
x  =  0.0953 
r  ~  0.04997 


1.91 


From    Table    61,  Sec.  7— for  —  =  1.91  and    80%  power-factor, 
find  a=  2.487 

From    Table    59,   Sec.   7— for  y  =  0.0    and    80%  power-factor, 

findb=  1.56 

From  Table  62,  Sec.  7 — for  single  phase  and  .80%  power-factor 
find  q  =  1.25 

e  =  2.06X2.487  =  5.125% 
p  =  2.06X1.56   =3.21% 
I0  =  1.25X227    =284  amperes. 

I0  is  within  the  current  carrying  capacity  of  the  No.  0000  stranded 
copper  T.  B.  W.  wire. 

_.  u     ,          5.125X220 
Volts  drop  = 


Power  loss  = 


100 

3.21X50 

100 


=  11.28  volts. 
=  1.605kw. 

[4751 


Sec.  7 


ELECTRICAL  CALCULATIONS 


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[476] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


TABLE  62 
•^ 

VALUES  OF  q 

2-PHASE,   3-WlRE 

Phase 

4-Wirea 

Outer 

Common 

3-Phase 

Wires 

Wire 

1.00 

1.00 

1.00 

1.00 

1.414 

1.154 

.95 

1.052 

1.052 

1.052 

1.488 

1.215 

.90 

1.111 

1.111 

1.111 

1.571 

1.282 

.85 

1.176 

1.176 

1.176 

1.667 

1.357 

.80 

1.250 

1.250 

1.250 

1.768 

1.443 

.70 

1.429 

1.429 

1.429 

2.02 

1.649 

.60 

1.667 

1.667 

1.667 

2.357 

1.923 

.40 

2.50 

2.50 

2.50 

3.535 

2.885 

.20 

5.00 

5.00 

5.00 

7.07 

5.77 

39.  Single-Phase  Three-Wire  Systems  are  calculated  in  a  manner 
similar  to  that  for  the  single-phase  2-wire  circuit,  using  the  voltage 
between  the  outside  wires  for  the  value  of  E. 

40.  Two-Phase  Three- Wire  Systems. 
Problem: 

How  far,  and  with  what  average  voltage  drop  can  500  kw.  at 
2,200  volts,  60  cycles,  and  85%  power-factor  be  transmitted  on  a 
two-phase,  three-wire  system,  using  No.  00  stranded  copper  wire, 
spaced  12  inches  from  center  to  center,  assuming  a  10%  power  loss. 

In  Table  45,  Sec.  3,  for  60  cycles  and  12"  spacing  find  x  =  0.1006. 

In  Table  36,  Sec.  3,  find  r=  0.07935. 

x      0.1006 


0.07935 


=  1.268 


Table  61,  Sec.  7  for  —  -  1.268  and  power-factor.of  85%    a  =  1.804. 

Table  59,  Sec.  7  for  y  =  0.0  and  power-factor  of  85%,     b  =  1.38. 
p  =  10 


13.1% 


Percent  volts  drop  e  =7.25X1.804 
WX1000 


I  = 


2E 


477  ) 


Sec.  7  ELECTRICAL  CALCULATIONS 

.  _  e'  10  E 
2rl 

,       500X1000 

=    2x2200  ==113<5  amPeres- 

7.25X10X2200    . 
-2X0.07935X  113.5  ~8'86 

The  power  loss  calculations  are  correct,  but  the  voltage  drop 

calculations  give  the  average  drop  on  each  phase.  The  leading 

phase  will  have  the  greatest  drop.  See  Art.  25,  Sec.  7. 

See  Table  62,  Sec.  7. 

q  =  1.667. 

I0  =  113.5X1.667=  189.4  amperes  in  the  common  wire. 

This  is  within  the  allowable  carrying  capacity  of  No.  00  stranded 
copper  T.  B.  W.  wire. 

If  the  common  wire  differs  in  size  from  the  outside  wires,  use  the 
average  resistance  as  r  in  the  formulae.  (The  resistance  of  one 
outside  wire  plus  the  resistance  of  the  common  wire,  divided  by 
two.)  Treat  the  reactance  in  the  same  manner.  Then  use  these 

average  values  to  find  —  and  proceed  in  a  similar  manner  as  when 
all  wires  are  of  equal  size. 

41.  Three-Phase  Transmission. 

The  following  problem  illustrates  the  effect  of  capacity  current: 
Find  the  power  loss  and  voltage  drop  in  per  cent,  when  trans- 
mitting 20,000  kw.  at  100,000  volts,  85%  power-factor,  on  a  three 
phase,  60  cycle  line  100  miles  long,  using  250,000  cir.  mil.  aluminum 
conductors,  spaced  10  feet  from  center  to  center. 

From  Table  51,  Sec.  3,  find  the  charging  current,  loc  per  1000  ft. 
of  line,  per  1,000  volts  =  0.0529  X10-2 

_  IocXlX5.28XE_0.0529  100,000 

1000 

Ic=  27.95  amperes. 

T      20,000X1,000 

2X100,000    =  10Q  amperes. 

Table  36,  Sec.  3.     For  aluminum  cable  r  =  0.0679  ohm. 
Table  45,  Sec.  3.     x=  0.1462  ohm. 
x      0.1462 

[478] 


ELECTRICAL  CALCULATIONS  Sec.  7 

Ic     27.95 


I        100 


=0.2795 


,     2  r  1  IJ2,  X  0.0679  X  5,280  X  100X100    -      ~ 
10  E  ~  10X100,000 

Table  59,  Sec.  7,  for  -y-=  .2795  and  85%    power-factor   find 
b  =  1.230. 

Table  60,  Sec.  7  for  b  =  1.230  find  power-factor  =  90% 

Table  61,  Sec.  7  for  90%  power-factor  and  —=2.16  find  a  =  2.18 


Table  62,  Sec.  7  for  90%  power-factor,  3-phase  find  q=  1.282 
e  =  7.16X2.18=  15.4% 


p  =  7.16X1.233=  8.68% 

I0  =  100X1.282=  128.2  amperes. 


Voltage   at   the   generator  =  1.154X100,000=  115,400  volts 
Power  at  the  generator  =  •  1.0868X20,000=  21,735  kw. 


cos. 


(1-154)2 
1.0868 

Apply  these  values  to  Table  59,  Sec.  7  and  find  b'=  1.219. 

In  Table  60,  Sec.  7  for  b'  =  1.219  find  90.5%  power-factor  at  the 
generator. 

The  rise  in  voltage  at  no  load  is 
57Xl2Xf2 


109 

57X100X100X60X60 
109 


=2.05% 


Therefore  the  actual  voltage  variation  at  the.  generating  station 
from  no  load  to  full  load  is  15,400+2,050=  17,450  volts. 

To  determine  if  the  conductor  is  of  sufficient  size  to  carry  the 
load  current,  obtain  q  from  Table  62  for  a  three-phase  circuit  and 
90%  power-factor.  q=  1.282. 

I0  =  1.282X100=  128.2  amperes. 

The  current  128.2  amperes  is  within  the  allowable  current  carrying 
capacity  of  a  250,000  cir.  mil.  cable.  (Sec.  3.) 

42.  Graphical   Solution   of   a   Three-Phase   Transmission   Line. 
The  proceeding  problem  is  solved  graphically  in  Fig.  297.     More 

[479] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


FIG.  297. 

accurate  values  will  be  obtained  by  the  graphical  method  if  drawn 
to  a  large  scale. 

Obtain  Ic,  I, — and  e'  in  the  same  manner  as  obtained  in  Article  41. 
Ic  =  27.95  amperes.     1=  100  amperes,  1~f=  0.1397 


—  =2.16;  e'  =  7.16.    In  Sec.  1,  for  cos.  0  =0.85  find  tan.  9  =  0.62. 

In  Fig.  297,  lay  off  OA  to  the  scale  of  E  =  100,000  volts.     Draw 
AB  from  A  and  parallel  to  OA  "=  = —  ~j7j() — " —  =  7,160  volts. 

At  90°  from  AB  draw  BC  =  ^'x-y-  =  100>0^QX7-16X2.16  =  15,450 

volts.  Draw  AC.  Draw  CD  at  right  angles  to  AC  and  through  the  point 
C.   Scale  AC  =  17,028  volts,  lay  off  CE  =  AC  Tan.  9  =  10,540  volts. 

From  E  lay  off  EF  toward  C,  equal  to  ACX-^-=  17028X0.1397  = 

2379  volts.     Connect  O  and  F  and  scale  this  distance.     The  value 
obtained  is  115,300  volts.     This  is  the  generator  voltage. 

Lay  off  OG  to  the  scale  of  1=  100  amperes.     Lay  off  OH=  I 
tan.  0=  100X0.62  =  62  amperes.      From  H  toward  O  lay  off  — HJ 

=  -~  =  13.97  amperes.    Draw  JK  and  GK  parallel  respectively  to 
OA  and  OH.    Draw  KL  from  K  and  at  right  angles  to  OF.    Lay  off 


KM  =  ~  X  -        = 
2  .b 

amperes. 


16.12.     Draw  OM  and  scale;    OM  =  103.5 


[  480  ] 


ELECTRICAL  CALCULATIONS  Sec.  7 

With  a  protractor  measure  the  angle  between  OM  and  OF.  This 
angle  is  24  degrees.  In  Sec.  1,  find  Cos.  (24°)  =  0.9135,  which  is 
the  power-factor  of  the  generator,  —  91.35%. 

The  per  cent  power  loss  is  found  as  follows: 

Single  phase: 
E'  Ig  cos.  6g  _ 
10W 

For  polyphase: 


2  X  115,400  X  103.5  X  0.9135       im  _  n  0^ 
P=  10X20,000 

Fig.  297  is  not  drawn  to  scale  as  the  values  of  AB,  BC,  etc.,  are 
so  small  in  comparison  to  OA  that  they  will  not  definitely  show  the 
construction.  Obiviously  however,  in  laying  this  off  an  exact  scale 
must  always  be  maintained.  The  values  for  power  loss  as  obtained 
graphically  and  as  obtained  from  calculation  do  not  agree.  The 
graphical  value  may  be  in  error,  since  large  quantities  are  calculated 
and  a  small  error  in  the  quantities  may  make  a  large  error  in  their 
difference. 

43.  Additions  to  Existing  Systems.  Where  the  voltage  of  a 
transmission  extension  is  fixed  due  to  its  connection  to  an  existing 
system,  the  calculations  may  be  greatly  simplified  by  means  of  a 
table,  such  as  Table  63.  This  has  been  calculated  from  Tables  59 
and  61. 

Table  63  gives  the  per  cent  power  loss  and  the  per  cent  voltage  drop 
per  1000  kw.  per  1000  feet  of  line  for  3  phase,  60  cycle,  13200  volt 
transmission,  with  a  separation  between  wires  of  24  inches.  Only 
four  sizes  of  wire  have  been  considered.  A  problem  will  show  the 
simplicity  of  this  method. 

Problem:  It  is  desired  to  transmit  5000  kw.,.  20,000  ft.  at  a 
power-factor  of  80%.  What  is  the  power  loss  and  voltage  drop  in 
per  cent? 

Solution.  It  is  necessary  to  use  a  No.  0000  copper  wire  in  order 
to  secure  proper  current  carrying  capacity.  (Table  64.) 

In  Table  63,  for  No.  0000  copper  wire  and  80%  power-factor  e  = 
0.0782  per  1000  ft.  per  1000  kw.  The  total  voltage  drop  is  0.0782  X 
5  X  20=  7.82%.  p  =  0.0438  per  1000  ft.  per  1000  kw.;  therefore, 
the  total  power  loss  is  0.0438  X  5  X  20=  4.38%. 

All  calculations  in  the  above  problems  have  been  made  with  a 
slide  rule.  No  corrections  were  made  for  change  in  resistance  due 
to  temperature.  This  may  be  readily  allowed  for,  however,  as 
shown  in  Sec.  3. 

16  [  481  ] 


Sec.  7  ELECTRICAL  CALCULATIONS 

When  large  cables  are  used,  it  is  also  necessary  to  correct  the 
resistance  for  the  skin  effect.  For  such  corrections  the  values  of 
resistance  taken  from  the  table  are  multiplied  by  the  factors  given 
in  Table  25,  Sec.  3. 

For  copper  covered  steel  wire,  the  resistance  in  the  table  must 
be  increased  by  the  percentage  indicated  in  curves  Figs.  78-81,  Sec.  3, 
for  copper  covered  steel.  The  increase  in  internal  inductance  of 
copper  covered  and  aluminum  core  steel  wire,  is  very  small  and  need 
not  be  considered.  However,  if  it  is  so  desired,  curves  Figs.  84-87 
shown  in  Sec.  3  for  copper  covered  steel  wire  may  be  used.  The 
percentages  there  given  apply  only  to  the  factors  0.0152  and  0.0305 
in  the  formulae  for  inductance. 

44.  Alternating  Current  Series  System. 
Symbols  : 

E   =  voltage  of  each  lamp. 
E'  =  voltage  at  the  generator. 
1     =  length  of  the  line  in  feet. 
I0   =  current  of  the  circuit  in  amperes. 
r     =  resistance  per  1,000  ft.  of  wire  in  ohms. 
cos.  0    =  power-factor  of  the  circuit. 
N  =  number  of  lamps. 
a    =  factor  in  Table  61,  Sec.  7. 
T?'     M   p    I    arllocos.  9 

~WcT~ 

Problem: 

Find  the  voltage  at  the  generator  when  No.  6  copper  wire  is  used 
to  transmit  energy  for  100,  60  cycle,  80  volt,  6.6  ampere  arc  lamps 
at  a  power-factor  of  70%.  The  total  length  of  the  line,  which  is 
erected  30  feet  from  the  ground,  is  20,000  ft. 

From  the  inductance  formulae,  Art.  29,  calculate  x  for  1,000  feet 
of  line. 

x  =  0.5342  (approximate). 
r  =  0.3944. 


In  Table  61,[for  70%  power-factor  and—  =  1.35  find  a  =  2.37 
I   E'-  (100X80)  +  (2.37X0.3944X^000X6.6X0.7) 

E'  =  8,000  +  86.4  =  8,086.4  volts 

From  this  it  may  be  seen  that  for  most  series  alternating  current 
circuits  the  line  cLrop  is  negligible. 

[  482  ] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


11 

C/D  pq 


^ 


B 


8  £ 
w  § 


H  g-. 

<cn 

il 
i* 

w  ^ 

Sg 


(  to  C-  J 
iH  TH  C 


S 


o 


S 


Sao  04  co 
eowTH 


ESIS 


Sas 


[  483  ] 


Sec.  7  ELECTRICAL  CALCULATIONS 

45.  CHOICE    OF    VOLTAGE    ON    TRANSMISSION   LINES. 

Some  of  the  conditions  determining  transmission  line  voltages 
are  as  follows: 

(1)  The  density  of  population  in  the  territory  through  which 
it  is  proposed  to  run  the  line.     This,  to  a  certain  extent,  deter- 
mines the  amount  of  load. 

(2)  The  character  of  the  district;   that  is,  whether  it  is  a  resi- 
dential or  a  mill  district,  which  determines  the  type,  power-factor 
and  diversity  factor  of  the  load. 

(3)  The  probable  extension  of  the  line  to  care  for  increased 
growth   in   the  section,  or  to   supply  energy  to  manufacturing 
establishments  in  territory  beyond. 

(4)  The  voltage  of  the  existing  system. 

(5)  The  ratio  of  the  proposed  load  to  the  station  load.     This 
determines  whether  or  not  it  is  desirable  to  operate  a  system  of 
different  voltage  requiring  special  transformers,  etc. 

(6)  Economic  conditions.     See  Art.  60,  Sec.  7. 

From  tables  71  and  72,  Sec.  7,  are  found  values  of  current  density 
under  certain  load  assumptions  for  different  cost  per  kw.  hour  and 
per  pound  of  conductor.  These  values  are  used  in  the  following 
formulae: 

E  =  transmission  voltage. 

1  =  length  of  the  line  in  feet. 

p  =  per  cent  power  loss. 

q  =  see  Table  62. 

c  =  current  density  in  amperes  per  cir.mil  (Tables  71  and  72.) 

p  =  resistance  per  mil  foot  of  conductor. 

k  =  2  for  single-phase  and  2-phase;  1.5  for  3-phase. 

Direct  current: 
E_  200,10 
P 

Alternating  current;   single  phase  and  polyphase. 
E  =  IQQpklcq 

P 

In  using  these  formulae  an  odd  voltage  is  nearly  always  obtained. 
It  is  generally  desirable  to  use  the  next  higher  standard  voltage 
as  the  radius  of  transmission  is  thereby  extended. 

46.  CORONA  AND  CORONA  LOSS.     When  a  given  potential 
gradient  in  the  air  surrounding  a  conductor  at  high  potential  is 
exceeded,  the  wire  becomes  luminous,  due  to  a  breakdown  of  the 
air.     This  phenomenon  is  called   Corona.     A  certain  amount  of 
energy  is  required  to  ionize  the  air  before  Corona  occurs.     For 
this  reason  the  visual  corona  forming  voltage,  is  higher  than  the  volt- 
age at  which  loss  would  otherwise  occur.     The  laws  of  corona  for- 

[484] 


ELECTRICAL  CALCULATIONS  Sec.  7 

mation  and  energy  loss  have  been  investigated  by  Mr.  F.  W.  Peek, 
Jr.,  and  the  formulae  devised  by  him  follow. 

The  loss  during  storms  is  considerably  greater  than  that  occurring 
in  fair  weather,  but  the  factors  controlling  it  are  so  varied  that 
mathematical  calculations  applying  thereto  are  very  intricate. 
Investigation  has  shown  that  fairly  accurate  results  may  be  ob- 
tained for  stormy  conditions  by  using  80%  of  the  voltage  at  which 
loss  occurs  during  fair  weather. 

Symbols : 

1     =  length  of  line  in  miles, 
n    =  number  of  wires. 

p   =  power  loss  in  kilowatts  per  mile  of  conductor, 
e    =  effective  kilovolts  to  neutral  (line  voltage). 
e0  =  effective  disruptive  critical  voltage  to  neutral  in  kilovolts. 
ev  =  effective  visual  critical  voltage  to  neutral  in  kilovolts. 
k'  =  552. 
go  =  53.6. 
=  17.91  b 

459 +t 

b     =  barometric  pressure  in  inches  of  mercury, 
t     =  temperature  in  degrees  fahrenheit. 
r     =  radius  of  conductor  in  inches, 
d    =  spacing  between  the  conductors  in  inches, 
f     =  frequency  in  cycles  per  second. 
m0  =  irregularity  factor, 
mo  =  1  for  polished  wires. 

mo  =  0.98  to  0.93  for  roughened  or  weathered  wires, 
nio  =  0.87  to  0.83  for  seven  strand  cables. 
mv  =  m0  for  wires. 

mv  =  0.72  for  local  corona  along  a  seven  strand  cable. 
mv=  0.82  for  decided  corona  along  a  seven  strand  cable. 

The  effective  disruptive  critical  voltage  to  neutral  is 

e0  =  2.302  m0  go  5  r  logic 

The  visual  critical  voltage  to  neutral  is 

ev  =  2.302  mv  go  r  (  logio  |  5  |  1  +  — ^ 

V  r  /     V        V] 

The  power  loss  in  kilowatts  is 

Power  loss  =  n  1  p 
k'     f 


[485] 


Sec.  7  ELECTRICAL  CALCULATIONS 

These  formulae  may  be  greatly  simplified  for  convenient  use 
by  calculating  tables  similar  to  inductance  tables.  Formulae  apply- 
ing to  these  tables  follow. 

E  =  effective  kilovolts  between  wires. 
e    =  effective  kilovolts  to  neutral. 

e0  =  effective  disruptive,  critical  voltage   to  neutral  in  kilo- 
volts. 

ev=  effective  visual  critical  voltage  to  neutral  in  kilovolts. 
P  =  total  energy  loss  in  kilowatts  due  to  corona  discharge. 

ki  =  104.5  XA/JL  Table  66. 

1  d 

k2  =  123.4  r  logio  -j-  Table  67. 

t  A    .  0.189\ 
V      Vsr/  Table  68' 


n   =  number  of  wires. 

1     =  length  of  line  in  feet. 

5    =  air   density   factor  =    45Q  ,  t          Table  65. 

The  remaining  factors  are  the  same  as  in  the  above  formulae. 

•pi 
For  single  phase     e  =  -~- 

Tji 

For  two  phase        e  =  -jr- 

Tji 

For  three  phase     e  =        •- 
v  3 

ev     =  mv  k2  kg 


108  6 

In  addition  to  the  condition  of  the  wire,  a  factor  which  has  great 
influence  on  corona  phenomena,  is  the  air  density  factor  5.  This 
varies  directly  with  the  barometric  pressure,  and  inversely  with 
the  absolute  temperature.  The  barometric  pressure  at  sea  level 
will  vary  from  a  maximum  of  about  30.90  inches  of  mercury  in  fair 
weather  to  29.00  inches  of  mercury  in  stormy  weather.  A  fair 
average  condition  being  29.92  inches. 

As  some  suitable  basis  must  be  chosen  in  all  calculations,  this 
value  of  29.92  inches  has  been  taken  as  a  basis  from  which  the  values 
of  5  were  calculated  for  different  temperatures  and  for  different 
altitudes.  These  values  of  8  have  been  inserted  in  Table  65. 

[  4861 


ELECTRICAL  CALCULATIONS 


Sec.  7 


s 

«5  r-(  IO  O  U3         O  0  «£1  LO  "*         Tl<  i-l  O  O  Tj< 

S;ss;ss  gsssss  is^iss 

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oo 

«S  T}(  CO  iH  «i<        OlAOt~<#        T-IO>O)(O>A 

sssss  sssggs  sssss 

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to 

§ 

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1 

& 

guaeoooo      ^<ei-i(oc4      <nmiAtno 
SSS§    S^SSS?    g£SS% 

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[487] 


Sec.  7  ELECTRICAL  CALCULATIONS 

If  it  is  desired  to  use  any  other  sea  level  barometric  pressure  than 
29.92  inches  as  a  basis,  calculated  corrections  should  be  made. 
(Sec,  11.)  Inspection  of  Table  65  will  show  that  an  increase  of  500 
feet  above  sea  level  makes  practically  the  same  difference  in  5  as 
an  increase  in  temperature  of  10°F.  To  extend  the  tables  for  tem- 
peratures beyond  the  range  given,  proceed  as  follows: 

If  it  is  desired  to  find  the  value  5  for  2000  ft.  above  sea  level  and 
a  temperature  of  120°F.  In  Table  65  for  2000  feet  and  90°  is  found 
the  factor  0.916.  120°  is  30°  above  90°,  therefore  by  adding  1500 
feet  to  2000  feet,  the  value  of  5  for  2000  feet  and  120°  is  found  to  be 
0.876;  the  value  for  3500  feet  and  90°F.  This  is  an  approximation 
only. 

The  values  of  ki  are  given  in  Table  66  for  various  distances  be- 
tween wires  and  for  various  sizes  of  wire,  both  stranded  and  solid. 
This  has  been  multiplied  by  a  constant  so  that  "1"  may  be  used  in 
feet  rather  than  in  miles  in  order  to  conform  to  the  other  tables. 

The  values  of  k2  in  Table  67  have  been  calculated  for  various 
distances  between  wires  and  for  various  radii  of  wires.  To  find  the 
visual  corona  forming  voltage,  it  is  necessary  to  use  the  value  of  k3 
which  has  been  calculated  for  various  values  of  8  and  for  various 
radii  of  stranded  and  solid  wire.  The  method  of  using  these  tables 
is  illustrated  in  the  following  problem. 

Problem: 

Find  the  power  loss  and  corona  forming  voltage  on  a  No.  00 
B.  &  S.  stranded  copper  wire,  located  6000  feet  above  sea  level, 
for  fair  and  stormy  weather;  on  a  three  phase,  three  wire,  60  cycle 
line,  100  miles  long,  operated  at  88,000  volts;  wires  spaced  10  feet 
apart  and  an  air  temperature  of  70°  F. 

1  =  528,000 
n=  3 

In  Table  65  for  70°  F  and  6000  ft.  5=  0.845 

Table  66  for  10  ft.  spacing  and  No.  00  stranded  copper  wire  ki  = 

4.38 
Table  67  for  10  feet  spacing  and  No.  00  stranded  copper  wire 

k2=  71.44 

For  No.  00  stranded  copper  wire  and  6=  0.845. 
Interpolate  Table  68  and  find  k3=  1.22 

m0  =  0.87         (See  symbols.) 
mv  =  0.72  for  local  corona  and 
mv=  0.82  for  decided  corona 

e     =  -?L  =  -^L  =  50.88  kilovolts. 


e0   =0.87X0.845X71.44=52.51 
ev   =0.72X71.44X1.22=62.76 

Fair  weather—  e  is  less  than  e0 

[488] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


TABLE  66 

VALUES  OF  Kt 

K!  =  104.5  xV~j- 

S  branded 

SEPARATION  OF  WIRES  IN  FEET 

2 

4 

G 

8 

10 

12 

500,000 
450,000 
400,000 

13.69 
13.28 
12.86 

9.82 
9.36 
9.11 

7.86 
7.64 
7.43 

6.85 
6.64 
6.38 

6.09 
5.94 
5.76 

5.57 
5.40 
5.26 

350,000 
300,000 
250,000 

12.44 
12.02 
11.60 

8.79 
8.46 
8.19 

7.16 
6.91 
6.69 

6.21 
5.98 
5.79 

5.55 
5.35 
5.19 

5.07 
4.89 
4.74 

0000 
000 
00 

10.98 
10.30 
9.77 

7.76 
7.30 
6.91 

6.34 
5.97 
5.65 

5.49 
5.17 
4.89 

4.91 
4.62 
4.38 

4.48 
4.22 
3.99 

0 
1 

9.24 
8.67 

6.53 
6.14 

5.33 
5.01 

4.63 
4.34 

4.13 
3.88 

3.77 
3.54 

Solid 

0000 
000 
00 

10.29 
9.66 
9.06 

7.24 
6.83 
6.45 

5.91 
5.58 
5.26 

5.12 
4.83 
4.56 

4.58 
4.32 
4.08 

4.17 
3.94 
3.71 

0 
1 
2 

8.60 
8.11 
7.67 

6.08 
5.72 
5.42 

4.97 
4.76 
4.75 

4.31 
4.06 
3.84 

3.85 
3.63 
3.41 

3.51 
3.36 
3.13 

3 
4 
5 

7.24 
6.83 
6.45 

5.11 
4.83 
4.56 

4.17 
3.94 
3.71 

3.62 
3.42 
3.22 

3.19 
3.05 
2.89 

2.96 
2.79 
2.63 

6 

6.08 

4.31 

3.51 

3.04 

2.69 

2.45 

Therefore        p  = 
Stormy  weather  p 


_  3X528,000X60X4 

0.845  X 10* 
=  389.0  kw. 


— -j"50.88-(0.8X52.51)l 


The  following  facts  should  be  noted: 

The  voltage  along  a  transmission  line  is  not  constant,  but  varies 
depending  upon  the  distance  from  the  station,  the  amount  of  load, 
the  power-factor,  etc.  Therefore,  the  power  loss  due  to  corona  is 
necessarily  a  summation  of  short  lengths  of  line,  in  which  the  voltage 
at  both  ends  is  assumed  to  be  equal.  When  corona  exists  on  a  wire, 

[489] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


TABLE  67 

VALUES  OF  K2 

K2  =  123.4r  logic  

Stranded 

SEPARATION  OF  WIRES  IN  FEET 

2 

1 

4 

6 

8 

10 

12 

500,000 
450,000 
400,000 

89.20 
85.26 
81.68 

104.38 
99.57 
97.25 

113.26 
106.72 
103.15 

119.59 
113.88 
108.20 

124.49 
118.44 
113.02 

127.20 
122.15 
115.48 

350,000 
300,000 
250,000 

77.36 
73.16 
69.59 

89.94 
84.76 
80.44 

97.35 
91.67 
86.86 

102.53 
96.73 
91.42 

106.60 
100.31 
95.00 

109.93 
103.39 
97.84 

0000 
000 
00 

64.03 
58.24 
53.30 

73.78 
67.00 
61.07 

79.58 
72.05 
65.76 

83.66 
75.76 
68.97 

86.86 
78.47 
71.44 

89.45 
80.81 
73.53 

0 
1 

48.74 
44.05 

55.77 
50.22 

59.84 
53.79 

62.68 
56.26 

64.90 
58.24 

66.75 
61.07 

Solid 

0000 
000 
00 

57.25 
52.31 
48.98 

65.76 
59.96 
55.89 

70.82 
64.53 
60.09 

74.40 
67.49 
62.92 

77.11 
69.95 
65.14 

79.33 
72.05 
67.00 

0 

1 
2 

43.55 
39.60 
36.15 

49.48 
44.91 
40.96 

53.05 
48.12 
43.68 

55.52 
50.34 
45.65 

57.50 
52.07 
47.25 

59.10 
53.42 
48.49 

3 
4 
5 

32.82 
29.86 
.27.14 

37.01 
33.56 
30.60 

39.48 
35.78 
32.57 

41.33 
37.38 
33.93 

42.69 
38.62 
35.04 

43.80 
39.60 
35.90 

6 

24.68 

27.64 

29.49 

30.72 

31.71 

32.45 

the  capacity  of  the  line  is  increased  due  to  the  increase  in  effective 
diameter. 

For  complete  details  covering  corona  phenomena  see  A.I.E.E. 
proceedings  of  July  1911,  June  1912  and  June  1913. 

47.  LOCATING  THE  CENTER  OF  DISTRIBUTION.  When 
several  loads  are  distributed  along  an  approximately  straight  line 
and  it  is  desired  to  locate  the  center  of  distribution,  the  method 
is  as  follows  (Fig.  298): 

Wi,  W2,  W3,  W4,  etc.,  denote  the  kilowatt  capacity  of  the  respective 
loads.  Through  Wi,  W2,  W8,  W4,  etc.,  draw  the  line  OX,  and  at 
any  point  on  the  line  OX  locate  a  point  O.  The  distance  from  this 

[  490  ] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


point  to  Wi,  W2,  etc.,  designate  as  li,  12,  la,  U,  etc.  These  lengths 
may  be  in  feet  or  in  miles  . 

Let  lx  =  the  distance  from  O  to  the  center  of  distribution  G, 
then: 

,   IiWi  +  12W2  +  13W3  +  l4W4  etc. 
Wi  +  W2  +  W3  +  W4  etc. 

In  which  lx  is  the  distance  from  O  (in  feet  or  miles  according  to 
the  values  of  \lf  12,  etc.)  to  the  center  of  distribution.  If  the  point 
O  is  taken  at  one  of  the  loads,  Wi,  the  equation  is  slightly  simplified. 
The  distances  in  this  case  are  measured  from  Wi,  and  therefore 
li  will  equal  zero,  and  the  equation  becomes 


lx 


12W2  + 


etc. 


W2  +  W3  +  W4  etc. 


The  distance  lx  is  laid  off  from  Wi  giving  the  same  point  G. 
The  power  loss  increases  as  the  square  of  the  distance  between  the 
actual  point  of  the  feed  and  the  point  G. 


0 

\\ 

-  <#  — 

V 

Si-3  ' 

f 

«                       7 

^       * 

FIG.  298. 

Where  loads  are  located  at  various  points,  not  on  a  straight  line, 
as  shown  in  Fig.  299,  the  following  procedure  is  adopted: 

Let 

Wi,  W2,  W3,   etc.  =  respective  loads. 

Draw  the  line  OX  through  any  convenient  point  so  that  the  loads 
are  all  located  on  one  side  of  the  line.  Draw  OY  at  right  angles 
to  OX  so  that  all  the  loads  are  included  in  the  angle  between  OY 
and  OX.  Let  1:,  12,  Is,  etc.,  be  the  distance  between  OY  and  the 
loads  in  feet  or  miles.  Let  l':,  1'2, 1'3,  etc,  be  the  distance  between 
OX  and  the  respective  loads.  Let  lx  be  the  distance  between  the 
center  of  distribution  G  and  OY  and  ly  be  the  distance  between 
the  center  of  distribution  G  and  OX. 
Then 


and 


lv  = 


A +W212+W,1«  etc. 
W!+W2+W3  etc. 


Wil'i+W2l'2+W3l'3etc. 


etc. 


[491] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


+ 


§ 


sss  sss  siS  RS  Iss  sis  ssl  a 


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[492] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


These  two  values  measured  respectively  from  OY  and  OX,  and  at 
90  degrees  from  the  same,  give  the  location  of  the  point  G. 

The  equations  may  be  slightly  simplified  by  taking  OX  and  OY 
through  one  of  the  loads.  If  OX  and  OY  are  drawn  through  W$ 
the  following  formulae  will  apply. 

WJi +WJ,  etc. 

lx   = 


and 


Wi+Ws+Wsetc. 

Wil'i+War2etc. 

W:+W2+W3etc. 

Distances  that  were  formerly  la  and  1'3  are   now   zero  and   the 
distance  llt  l\,  12,  1'2,  etc.  are  measured  from  OX  and  OY  running 


/J 


^ 


FIG.  299. 

through  W3;  lx  and  ly  are  measured  from  these  lines  passing  through 
W3  giving  the  same  location  of  G  as  before.  The*power  loss  increases 
as  the  square  of  the  distance  between  the  location  of  the  actual 
point  of  feed  and  G.  If  OX  and  OY  in  Fig.  299,  or  the  point  O  in 
Fig.  298,  are  located  between  the  loads  so  that  some  of  the  loads 
fall  on  one  side  and  some  on  the  other  side  of  the  lines  or  point,  it 
is  necessary  to  place  a  negative  sign  before  the  loads  times  the 
distances  on  one  side  of  the  lines  or  point,  and  a  positive  sign  before 
the  loads  times  the  distances  on  the  other  side  of  the  lines  or  point. 

In  calculations  for  alternating  current  systems,  the  kilovolt 
amperes  of  the  load  should  be  used  rather  then  the  kilowatts,  i.e. 
Wi,  W2,  etc.  equal  the  kilovolt  amperes  of  the  respective  loads. 

Also,  when  making  the  above  calculations  care  must  be  taken 

[493] 


Sec.  7  ELECTRICAL  CALCULATIONS 

to  use  the  actual  lengths  of  the  distribution  lines  rather  than  the 
air  lines,  provided,  however,  that  this  manner  of  calculation  does  not 
hopelessly  complicate  the  problem. 

48.   CALCULATION   OF  TRANSFORMER   CAPACITY. 

Let 

W  =  the  total  kw.  capacity  of  the  delivered  load, 
cos.  6     =  the  power-factor  of  load. 

q    =  the  factor  given  in  Table  62,  Sec.  7,  for  different  systems 

and  power-factors. 

kv-a      =  kilovolt    ampere    capacity  of  each  single  transformer 
in  the  bank. 

E  =  the  effective  voltage  on  any  system,  i.e.  on  a  single 
phase,  3-wire  system,  it  is  the  voltage  between  the  out- 
side wires.  On  a  3-phase  Y  connected  system,  it  is 
the  delta  voltage;  on  a  2-phase,  3-wire  system,  it  is  the 
voltage  between  the  common  wire  and  the  outside  wire. 
On  a  2-phase,  5-wire  system,  it  is  the  voltage  between 
the  phase  wires  and  not  from  the  neutral  to  the  phase 
wires.  In  all  other  systems  it  is  the  voltage  between 
phase  wires. 

I0    =  line  current. 

Et   =  voltage  across  transformer  primary  winding. 

It    =  the  current  in  the  transformer  primary  winding. 

E9  =  voltage  of  secondary  system  and  bears  the  same  re- 
lation to  the  manner  of  connection  as  E  in  the  primary. 

Is    =  the  secondary  line  current. 

E't  =  the  voltage  across  transformer  secondary  winding. 

I't   =  current  in  the  transformer,  secondary  winding. 

Table  69  gives  the  ratio  that  these  various  factors  bear  to  one 
another. 

(I)  Problem: 

Find  the  capacity  of  three  transformers  required  to  transmit 
1,200  kilowatts  at  80%  power-factor.  The  system  is  three  phase, 
three  wire  A  primary  and  Y  secondary. 

1st  Method: 

W  1200 

kv-a.  of  each  transformer  is  ^-TT -=    .,       =  500  kv-a. 

o  x  cos.  y 


kv-a. 


2xvr 

In  this  problem,  the  first  method  is  the  more  simple.     Assuming 
2,200  volts  between  primary  wires  and  220  volts  between  secondary 

[494] 


ELECTRICAL  CALCULATIONS  Sec.  7 

wires,  the  primary  and  secondary  current  of  each  transformer  is 
found  as  follows: 

W  1,200,000 


=  393.5  amperes. 


VSEcos.G      v  3X2,200X0.8 
The  current  in  each  transformer  primary  winding  is: 

I0      394 

=  Vjf  =  v7?  =        amPeres- 
The  voltage  of  each  transformer  primary  winding  is: 

Et  =  E  =  2200  volts. 
The  current  in  each  transformer  secondary  winding  is: 

I't  =  Is  =  3935  amperes. 
The  voltage  of  each  transformer  secondary  winding  is: 

E't=  -^  =  ^  =  127  volts. 
V3     V3 

Assume  that  all  conditions  are  similar  except  that  the  secondary 
is  a  three-phase  four-wire  system   and   the  potential  is  220  volts 
between  the  neutral  wire  and  the  outside  wires. 
Then, 
E8  = 

_          1,200,000 

V3X220  V3X0.8 
I't  =  Is  =  2,270  amperes. 

K      220V£  ^ 

V3         V3 

(II)  Problem: 

A  load  of  1,200  kilowatts  at  80%  power-factor  is  to  be  transformed 
from  2,200  volts,  three-phase,  three-wire,  to  220  volts,  three-phase, 
three-wire,  using  V  or  open  delta  connections.  Find  the  transformer 
capacity. 

1st  Method: 

TTH-  1  onn 

kv-a.  =  —j=  -  =    /—    —  =866  kilo  volt-amperes. 
Vs  cos.  9     V3X0.8 

2nd  Method: 

W  1  9OO 

-IL  q=  iL^xlt443=:  866  kilovolt-amperes. 
2i  2> 

[495  ] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


TABLE  69 
CALCULATION  OF  TRANSFORMER  CAPACITY 

Values  of  Symbols 

kv-a         CAPACITY  OF  EACH  TRANSFORMER 

System 

kv-a 

kv-a 

«, 

It 

Primary 
Connec- 
tion 

Single  <t> 
2  and  3  wire 

2.J.3, 
4  and  5  wire 

3  </>,  3  and 
4  wire 

3  <J>,  3  and 
4  wire 

3  0,  3  and 
4  wire 

3  phase 
4  wire 

3  phase 
3  wire 

3  <J>  Teaser 
Transformer* 

2</>to 
3  (/>  Main 

Transformer 

3  (j>  to 
2  $  Teaser 
Transformer* 

3  </>  to 
2  <j>  Main 
Transformer 

W 

Wq 

Wq 
2 

Wq 

E 
E 
E 

E 
E 

IP 

V3 

IP 
Io 

A 
A 
Y 
Y 
V 
•H 

T 

i 
1 

Cos.  e 
w 

2Cos.  6 

w 

3Cos.  0 

w 

2V3 
Wq 

3Cos.  0 

w 

2V3 
Wq 

3Cos.  6 

w 

2\/3 

Wq 
2V3 

Wq 

2 

Wq 

2 

Wq 

E 

3Cos.  0 

w 

E 
E 
E 

V3E 

V3  Cos.  0 
W 

2Cos.  0 
W 

2Cos.  0 
W 

2 

2Cos.  0 
W 

4 

Wq 
2 

2 
E 

\/3  Cos.  0 

*  Assumes  the  teaser  transformer  wound  for  86.6%  of  the  line  voltage;  if 
an  86.6%  tap  is  used  the  capacity  is  the  same  as  the  main  transformer. 

[  496  ] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


TABLE  69  —  Continued 
CALCULATION  OF  TRANSFORMER  CAPACITY 
Values  of  Symbols 

kv-a         CAPACITY  OF  EACH  TRANSFORMER 

System 

kv-a 

E't 

I't 

Secondary 
Connec- 
tion 

Single  $ 
2  and  3  wire 

2<}>  3, 
4  and  5  wire 

3  <J>,  3  and 
4  wire 

3  </>,  3  and 
4  wire 

3  4>,  3  and 
4  wire 

3  phase 
4  wire 

3  phase 
3  wire 

2  <J>  to 
3  (/>  Teaser 
Transformer* 

2<f>to 
3  <f>  Main 

Transformer 

3  4>  to 
2  (/>  Teaser 
Transformer* 

3*  to 
2  *  Main 
Transformer 

W 

Wq 

Wq 
2 

Wq 

Es 
Es 

Es 

Is 
Is 
Is 
I 

Y 

A 
A 
Y 
V 
-1 

1 
t 

-*J_ 

r 

t 

Cos.  e 
w 

2Cos.  0 
W 

3Cos.  0 
W 

2V3" 
Wq 

V3 
E3 

Ea 
Es 

3Cos.  0 

W 

3CosT0 

W 

2A/JT 
Wq 

V3~ 

Is 

V3^ 

IS 
Is 
Is 

I8 

Is 
Is 

2\/3^ 
Wq 

3Cos.  0 
W 

Vscos.  e 
w 

2V3 

Wq 
2 

A/3Wq 

V3~ 
ES 

\/3Es 
2 

Ea 
Es 

Es 

2Cos.  e 
w 

4 

Wq 
2 

Wq 

2 

Wq 
2 

V3Cos.  0 
W 

2Cos.  0 
W 

2Cos.  0 

*  Assumes  the  teaser  transformer  wound  for  86.6%  of  the  line  voltage;  if 
an  86.6%  tap  is  used  the  capacity  is  the  same  as  the  main  transformer. 

[497] 


Sec.  7  ELECTRICAL  CALCULATIONS 

In  this  problem  the  second  method  is  the  more  convenient. 

The  primary  voltage  and  current,  and  the  secondary  voltage  and 
current  equal  the  line  voltage  and  current. 

For  polyphase  transformers  it  is  only  necessary  to  determine 
the  total  kv-a.  by  dividing  the  energy  in  kilowatts  by  the  power- 
factor.  The  capacity  of  the  individual  windings  are  determined 
by  the  manufacturers. 

NOTE  :  Many  attempts  have  been  made  to  so  connect  transformers 
on  a  polyphase  system  that  each  single  phase  load  will  be  balanced 
on  the  polyphase  system.  It  is  possible  to  so  connect  transformers 
that  the  currents  delivered  to  the  single  phase  load  from  each  phase 
of  a  polyphase  system  will  be  equal,  but  in  such  cases  the  power- 
factors  will  vary  greatly.  The  fact  that  the  transfer  of  energy  in  a 
single  phase  system  is  pulsating  while  that  in  a  polyphase  system  is 
continuous  indicates  that  it  is  impossible  to  preserve  balanced  condi- 
tions on  a  polyphase  system  for  each  single  phase  load  without  the 
aid  of  rotating  machinery,  in  which  the  energy  from  the  polyphase 
system  may  be  stored  in  the  rotating  element  of  the  machine  in  the 
form  of  mechanical  energy  during  the  period  of  zero  energy  transfer 
in  the  single-phase  system. 

49.  Calculation  of  Transformer  Regulation.  The  regulation  of 
constant  potential  transformers  is  the  ratio  of  the  rise  of  secondary 
terminal  voltage  from  rated  non-inductive  load  to  no  load  (at 
constant  primary  impressed  terminal  voltage)  to  the  secondary 
terminal  voltage  at  rated  load.  (A.I.E.E.)  This  is  for  100% 
power-factor  only,  but  holds  true  for  other  power-factors  if  in  the 
definition  "inductive  load"  is  substituted  for  " non-inductive  load." 
The  regulation  of  a  transformer  may  be  calculated  by  several 
methods  when  the  resistance,  the  reactance,  and  the  magnetizing 
current  are  known,  one  of  which  follows: 
Let 

r     =  the  total  resistance  of  the  transformer  coils  referred 

to  the  primary. 
x     =  the  total  reactance  of  the  transformer  coils  referred 

to  the  primary. 

kv-a.    =  capacity  of  transformer  in  kilovolt  amperes. 
E     =  impressed  primary  voltage. 
I      =  energy  component  of  load  current, 
cos.  0    =  power-factor  of  the  load  as  a  decimal. 
Im  =  magnetizing  current. 
Ie    =  exciting  current  of  transformer. 
We  =  core  loss  in  watts. 

Formulae : 

_  kv-a.  X  cos.  6X 1000 
E 


[498] 


ELECTRICAL  CALCULATIONS  Sec.  7 

rl 


a0— a 
tan.  a   =  -^ 


reg.  %=  100  [ 


1  +e+e  a0  a 
cos.  a 


For  most  purposes  cos.  a  is  so  near  unity  that  it  may  be  neglected 
and  the  formulae  then  become 

reg.  %  =  100[e+eaoaJ 

The  magnetizing  component  of  the  no-load  current  may  be  found 
as  follows: 

cos.  We 


EIe 
Im        =  -^r-  tan.  ft 

If  the  power-factor  of  the  load  is  leading,  tan.  6  becomes  negative, 
but  the  remainder  to  the  formulae  is  the  same. 

Problem: 

Find  the  regulation  at  100%,  and  80%  (inductive  load)  power- 
factor  of  a  10  kv-a.  2,000  volt  transformer  having  8  ohms  resistance 
and  32  ohms  reactance  referred  to  the  primary  winding.  The 
exciting  current  =  0.5  amperes.  The  core  loss  is  600  watts. 


In  Sec.  1  for  cos.  ft  =0.6  find  tan.  0  =  1.327 
fiftfl 

Im  =  ^X  1.327  =0.398 

For  100%  power-factor 
10,000X1. 


•     T.«fe* 

32 
ao    =  -g-=4 

[  499] 


Sec.  7  ELECTRICAL  CALCULATIONS 

tan.  0=o 
Im        0.398 


I  5 


=  0.0796  =  a 


4-0.0796  3.9204      .-_._ 

tan.  a  =   —  -        -  =—5—:^  =0.0765 

-^+(4X0.0796)  +  ! 
In  Sec.  1  for  tan.  a  =  0.0765  find  cos.  a  =0.997 


reg  %=  100..._1   .  29% 

By  the  more  simple  formula 

reg.  %  =  100  Fo.02  +  (0.02X4X0.0796)]!  =2.64% 

For  80%  power-factor 

10,000  x  0.8 

2,000        =4  Amperes 

8X4  =0.016 


2,000 
ao   =4 
tan.  0    =  0.75  when  cos.  0=0.8 


a    =0.75+0.0995  =  0.8495 

tea.    a  =      ,       4~°-8495  -  =0.0471 

aoT6+(4X0.8495)  +  l 
Find  cos.  a  =  0.999 

reg.%=  100 

By  the  shorter  method 
reg.%=  100  [0.016  +  (0.016X4X0.8495)]  =  7.04%. 

50.  Calculation  of  Transformer  Efficiency.  The  efficiency  of 
a  transformer  is  the  ratio  of  the  power  output  to  the  power  input. 
The  all-day  efficiency  of  a  transformer  is  the  net  power  output 
for  24  hours  divided  by  the  gross  power  input  for  24  hours. 

W   =  kilowatts  output  (maximum). 

r      =  resistance  of  transformer  coils  referred  to  the  primary. 

[500] 


ELECTRICAL  CALCULATIONS  Sec.  7 


J0    =  primary  load  current. 
we   =  core  loss  in  watts. 

I  W 

0        E  cos.  6 

W 


r w 1 

Efficiency  %  =  100  I          we+rlo2 

L        "    1,000    J 

efficiency  of  a  transforme 
24  W  L  1 

24  W  LI  24  we     224  rF 
24  W  L+  1QOO   1     100Q  J 


The  all-day  efficiency  of  a  transformer  expressed  in  per  cent  is: 
=  100 


In  the  above  equation  all  the  symbols  are  the  same  as  previously 
used  with  the  addition  of  L  for  the  load  factor  as  a  fraction  and 
S  24  rl2,  which  is  the  summation  of  the  power  loss  in  resistance, 
where  I  is  equal  to  the  square  root  of  the  mean  square  of  the  current 
flowing  for  24  hours  and  r  is  the  resistance  of  the  transformer  coils 
referred  to  the  primary. 

VOLTAGE  REGULATORS 

51.  General.     Automatic  voltage  regulators  for  pole  line  use 
permit  better  regulation  and  service  from  a  long  line  with  regularly 
distributed  consumers  for  the  greater  part  of  its  length.     When 
regulators  are  installed  along  the  line  it  becomes  necessary  to  make 
calculations  of  regulator  capacity  and  per  cent  regulation  for  various 
consumers'  demands.     Transformers  may  be  used  to  increase  the 
line  voltage  at  a  given  point,  but  do  not  improve  the  line  regulation, 
as  the  voltage  addition  is  constant. 

52.  Regulation.     To  calculate  the  range  of  regulation  necessary, 
data  are  required  covering  the  variations  of  voltage  at  the  point 
where  the  regulators  are  to  be  installed. 

53.  Single-Phase  System.     (Fig.  300.) 

Let 

V  =  the  maximum  effective  voltage  variation  in  volts. 
E  =  average  effective  line  voltage  between  outside  wires. 
e   =  per  cent  of  regulation  of  regulators. 
Then 


The  reason  the  percentage  voltage  regulation  of  a  regulator  is 
one-half  the  voltage  variation  of  the  line,  lies  in  the  fact  that  voltage 
regulators  are  so  designed  that  the  secondary  voltage  coil  adds  to, 

[  501  ] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


or  subtracts  from  the  line  voltage,  thus  giving  the  regulator  double 
the  range  of  the  voltage  of  the  secondary  coil. 

54.  Two-Phase  System.     If  two  single-phase  regulators  are  used, 
the  calculations  are  the  same  as  for  a  single-phase  system.     If  a 


~T 

£ 
\ 

"-'VVVVVV"- 

1  —  AAA/VWVWWV— 

t 

FIG.  300. 

two-phase  regulator  is  used  V  is  the  average  of  the  phase  voltages; 
otherwise  the  calculations  are  identical. 

55.  Three-Phase,  Three-Wire  System.  Single-phase  or  poly- 
phase voltage  regulators  may  be  used  for  this  service.  When  single- 
phase  regulators  are  employed  they  should  all  have  the  same  reg- 


i     t 

£ 
I 

rvvvvvv^ 

L-VWWWVWVSAr- 

f 

n 

r-VWVWWWW- 

—  LAAAAAA^ 

1  ?' 

FIG.  301. 


! 

* 

^VVVVVV 
L>AAAAAAAAAAAA^ 

A"    1 

L! 

^A  A  A  A  A  A  A  

i                  "     V  V  V  V  V  V 
£           '                    WwWWWWVAr-i 

—I  i              JA^AAAAA/N  — 

FIG.  302. 

ulating  characteristics.  If  two  regulators  are  used,  connected  as 
in  Fig.  301  the  calculations  for  per  cent  regulation  are  the  same  as 
for  single-phase  regulators.  If,  however,  three  regulators  are  con- 
nected "A"  as  illustrated  in  Fig.  302,  the  per  cent  regulation  must 
be  found  by  the  following  formulae: 

[  502  ] 


ELECTRICAL  CALCULATIONS 

Accurate  formulae : 


Sec.  7 


e=  100 


/-"•(I)' 
V  (¥)'- 


Approximate  formulae  (less  than  ^  of  1%  error  for  commercial 

ranges) 

100  V 


e  = 


3E 


The  calculations  for  a  polyphase  regulator  are  the  same  as  for  a 
single-phase  regulator  with  the  exception  that  V  is  the  average 
of  the  three-phase  voltages. 

56.  Three-Phase,  Four-Wire  System.  Three  single-phase  units 
may  be  used  on  this  system  connected  between  the  neutral  wire  and 
the  outside  wires.  In  such  cases,  if  V  is  "A"  voltage,  E  should 
be  "A"  voltage;  if  V  is  Y  voltage,  E  should  be  Y  voltage,  and  the 
solution  remains  the  same  as  for  a  single-phase  system.  (Fig.  303.) 

Calculations  for  polyphase  regulators  are  made  in  the  same 
manner  as  for  the  three-phase  three-wire  system. 


I 

—  fVVVVVV'  f  —    —  3 

WvAAAAAAAA/WV-J       /-/-^ 
AAAAAAA'          ^ 

f 

\        E 

1     i 

I     £     LvVAAAAAAAAAAyV-" 
•V5~             -A  A  A  A  A  A  A 

¥ 

f 

i 

~  V  V  V  V  V  V     i       /-^y  4 

LwvwCvCwwM    3C3     At"7;''/ 

FIQ.  303. 

57.  Regulator  Capacity. 

Let 

I0  =  the  effective  line  current, 
kv-a.  =  kilo  volt  ampere  capacity,  of  regulator. 
E   =  effective  line  voltage, 
e    =  the  per  cent  regulation. 

Then 

(1)  The  capacity  of  a  single-phase  regulator  on  a  single-phase, 
or  of  each  of  two  single-phase  regulators  on  a  two-phase  system  is 

I0eE 


kv-a. 


105 


[503] 


Sec.  7  ELECTRICAL  CALCULATIONS 

(2)  The  capacity  of  each  of  two  or  three  regulators  connected  to 
a  three-phase,  three-wire  system,  as  shown  in  Figs.  301  and  302.  is 

I0eE 
kv-a-=-TtfT 

(3)  The  capacity  of  each  of  the  single-phase  regulators  on  a  three- 
phase,  four-wire  system  is  (Fig.  303) 

I0Ee 


If  E  is  "A"  voltage. 
Case  (2)  kv-a.  = 


If  E  is  Y  voltage. 

(4)  The  capacity  of  a  two-phase  regulator  is 
2I0Ee 


The  capacity  of  a  three-phase  regulator  is 

Case(l)kv-a.=  V3^Ee 
If  E  is  the  "A"  voltage,  and 


If  E  is  the  Y  voltage. 

If  a  transformer  is  used  the  per  cent  increase  in  voltage  is  fixed 
by  the   ratio  of  transformation: 

Let 

'    n=  the  ratio  of  transformation,  all  other  quantities  remaining 

100 
the  same  -as  before.     The  percent  voltage  increase  is  e  =  — 

The  transformer  capacity  is  found  by  the  following  formulae: 
E  I0    _  e  E  I0 


kv-a. 


1000  n        105 


Therefore  the  formulae  used  to  find  regulator  capacities  may 
be  used  for  transformers. 

Problem:  The  voltage  of  a  2,200  volt  single-phase  line  varies 
110  volts.  The  line  current  is  100  amperes.  Find  the  percent 
regulation  and  kv-a.  capacity  of  the  regulator  required  to  correct 
this. 

[  504  ] 


ELECTRICAL  CALCULATIONS  Sec.  7 

_  110X100, 
2X2,200 

100X2.5X2,200 
kv-a.     =  -      — g^=    —  =  5.5  kv-a. 

58.  RESULTANT    POWER-FACTORS.     Where    several    loads 
of  different  power-factors  are  connected  to  the  same   feeder,  the 
resultant  power-factor   may  be  found  by  means  of  the  following 
formulae: 

Symbols: 

Wi    =  kilowatts  supplied  to  Load  No.  1. 
cos.  61    =  power-factor  of  Load  No.  1. 

w2    =  kilowatts  supplied  to  Load  No.  2. 
cos.  02    =  power-factor  of  Load  No.  2. 

w3    =  kilowatts  supplied  to  Load  No.  3. 
cos.  03    =  power-factor  of  Load  No.  3,  etc. 
cos.  0r  =  resultant  power-factor. 
Then 

Wi  tan  0i+w2  tan  02+w3  tan  03  etc. 

tan.  0r     =  ; ; 7 

Wi+W2+w3  etc. 

Find  tan  0i,  tan  02  etc.  from  cos.  0i,  cos.  02  etc.  in  Sec.  1. 
Find  cos.  0r  from  tan  0r  in  Sec.  1. 

Problem: 

Find  the  combined  power-factors  of  200  kw.  at  70%  power-factor, 
100  kw.  at  80%  power-factor,  and  50  kw.  at  50%  power-factor. 

cos.  0i=  0.70        tan.  0i=  1.0176 
cos.  02  =  0.80        tan.  02  =  0.75 
.     cos.  03=  0.50        tan.  03=  1.732 

200X1.0176  +  100X0.75+50X1.732     ,  n,0 
tan-6r=  200  +  100+50 

Power-factor  =  cos.  0r  =  0.692. 

59.  Power-Factors  of  Various  Types  of  Loads.     Values  in  Table 
70  have  been  calculated  for  various  ratios  of  "connected  lighting 
to  connected  power  load.     Large  and  small  capacity  motors,  loaded 
with  an  average  load  of  about  one-quarter  full  load  and  three- 
quarters  full  load,  have  been  used.     This  combination  may  give 
much  lower  or  higher  power-factors,  depending  upon  the  type  of 
machinery  used.     Motors  from  ^  to  3  H.P.  are  considered  small 
motors,  and  motors  from  5  H.P.  to  50  H.P.,  large  motors. 

Symbols. 

w  =  connected  kw.  of  incandescent  lighting. 
Wi=  connected  h.p.  of  motorsXO.746 

[  505  ] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


TABLE  70 

POWER-FACTORS 

Relative  propor- 
tions of  lighting 
to  power,  con- 
nected load 

Large  motors 
at  M  load 

Large  motors 
at  M  load 

Small  motors 
at  M  load 

Small  motors 
at  %  load 

W=l 

Wi=0 

1.00 

1.00 

1.00 

1.00 

W=.75 
Wi=  .25 

.99 

.98 

.97 

.96 

W  =.5 

.95 

.90 

.90 

.80 

W  =.25 
Wi=.75 

.90 

.75 

.80 

.60 

W  =0 
Wi=l 

.85 

.40 

.70 

.35 

60.  ECONOMICS  OF  TRANSMISSION.  Economic  conditions 
cannot  be  formulated  with  any  great  degree  of  accuracy.  In  many 
cases  it  is  necessary  to  keep  down  initial  expense,  even  at  consider- 
able sacrifice  otherwise,  or  economy  in  a  certain  direction  may 
be  sought  at  the  expense  of  economy  in  some  other  direction.  For 
these  reasons,  it  is  necessary  that  individual  skill  and  judgment 
be  used.  In  general,  however,  use  may  be  made  of  Kelvin's  law: 
that  the  greatest  economy  is  obtained  where  the  interest  deprecia- 
tion and  taxes  on  the  investment  are  equal  to  the  cost  of  the  total 
power  losses  in  the  line  per  year.  As  the  market  for  power  and  light 
is  usually  uncertain,  and  the  proportion  of  power  to  light  unknown 
except  within  wide  limits,  the  total  amount  required  can  only  be 
determined  by  future  conditions.  An  approximate  estimate  of 
the  average  load,  even  after  the  most  careful  investigation,  defies 
accurate  calculation.  Thus,  the  following  tables  must  be  used 
with  the  utmost  care,  and  are  only  included  herein  that  they  may 
give,  in  part,  a  general  idea  of  the  conditions  affecting  the  line  itself, 
but  do  not  include  such  conditions  as  cost  of  right-of-way,  cost 
of  the  type  of  structure  to  be  erected,  and  the  many  other  features 
which  oftimes  influence  the  location  of  the  line  and  the  investment 
that  can  be  made  in  conductors. 

Symbols: 

Wm  =  weight  of  conductor  in  Ibs.  per  cir.  mil  foot. 
p    =  resistance  per  cir.  mil  foot, 
a     =  area  of  conductor  in  cir.  mils, 
n    =  ratio  of  total  power  loss  to  loss  in  one  wire  of  system  used. 

[  506  ] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


TABLE  71 
VALUES  OF  K4 

Cost 
of 
En- 
ergy, 
cents 
per 
Kw- 
hr. 

COST  OP  METAL,  CENTS  PER  POUND 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

H 

i)4 

2 

|» 

6.32 
4.47 
3.65 
3.16 

2.58 
2.24 

6.63 
4.69 
3.82 
3.32 

2.70 
2.34 

6.93 
4.90 
4.00 
3.46 

2.82 
2.45 

7.2 
5.1 
4.16 
3.6 

2.94 
2.55 

7.48 
5.29 
4.32 
3.74 

3.05 
2.64 

7.75 
5.47 
4.47 
3.87 

3.16 
2.74 

8.00 
5.65 
4.62 
4.00 

3.25 
2.82 

8.25 
5.83 
4.76 
4.12 

3.36 
2.92 

8.48 
6.0 
4.90 
4.24 

3.46 
3.00 

8.71 
6.16 
5.04 
4.35 

3.56 
3.08 

8.94 
6.32 
5.16 
4.47 

3.65 
3.16 

2.00 
1.82 

2.10 
1.91 

2.19 
2.00 

2.28 
2.08 

2.36 
2.16 

2.45 
2.24 

2.52 
2.31 

2.60 
2.38 

2.68 
2.44 

2.76 
2.52 

2.82 
2.58 

DI   =  ratio  of  total  weight  of  conductors  used  to  weight  of  one 

conductor. 
I0   =  maximum  effective  load  current. 


1  =  length  of  line  in  feet. 

GI  =  cost  of  conductor  per  Ib. 

C2  =  cost  of  energy  per  kw-hr. 

i  =  interest  as  a  decimal. 

d  =  depreciation  as  a  decimal. 

t  =  taxes  as  a  decimal. 

h  =  number  of  hours  of  operation  per  year. 

Considering  the  load  constant  the  total  cost  of  the  kw-hrs.  lost 
per  year  in  cents  is 


Power  cost 


I02hc2 


1000  a 


No.  1 


The  investment  cost  per  year  is 

Investment  cost=  ni  wm  a  1  GI    (i+d+t)  No.  2 

One  and  two  must  be  equal  according  to  Kelvin's  law 


n 

Pi 

V 

h  c2 

=  n 

i  wm  a 

1C: 

(i+d+t) 

1000 

a 

I( 

.  «E 

ii  Wm  Ci  (i+d+t) 

1000 

rii  Wm 

(i+d+t) 

1000 

I 

{  •' 

V 

Pn 

h  c2 

\ 

[  507  ] 

p  n 

h 

XA  /  — 


Sec.  7 


ELECTRICAL  CALCULATIONS 


TABLE  72 

VALUES  K5  =  VALUES  IN  TABLE  X-^-6 

Copper 
/^i    -i 

Alu- 

System 

Size  of  Wires 

{W|P??r 

dad 

Af\O7 

minum 

*U  /c 

20°  C. 

20°  C. 

2  wire  D.C. 

122 

74.5 

53. 

3  wire  D.C. 

Neutral  equal  to 

outside 

150 

91 

65 

3  wire  D.C. 

Neutral  one-half 

outside 

137 

83 

59.5 

Single-phase    A.C.     two- 

wire 

122 

74.5 

53 

Single-phase  A.C.   three- 

Neutral  equal  to 

wire 

outside 

150 

91 

65 

Single-phase  A.C.   three- 

Neutral  one-half 

wire 

outside 

137 

83 

59.5 

Two-phase    three-wire 

Common  wire  equal 

to  outside 

106 

64.5 

46 

Two-phase    three-wire 

Common  wire  1.41 

times  outside 

122 

74.5 

53 

Two-phase  four-wire 

122 

74.5 

53 

Two-phase  five-wire 

Neutral  equal  to 

outside 

137 

83 

59.5 

Two-phase  five-wire 

Neutral  one-half 

outside 

130 

79 

56.5 

Three-phase  three-wire 

122 

74.5 

53 

Three-phase   four-wire 

Neutral  equal  to 

outside 

141 

86 

61.5 

Three-phase   four-wire 

Neutral  one-half 

outside 

132 

80.5 

57.5 

wm  ci  (i+d+t)  1000 
P  n  h 


c  = 


It 


The  above  formulae  indicate  that  the  current  density  in  amperes 
per  circular  mil  area  is  proportional  to  the  square  root  of  a  factor 
depending  upon  the  number  of  wires,  the  weight  and  resistance  per 
mil  foot,  the  number  of  hours  used  and  the  interest  depreciation 
and  tax  cost  times  the  square  root  of  the  ratio  of  the  cost  of  material 
to  the  cost  per  kw-hr.  of  energy.  In  Table  71  values  of  K4  have 
been  calculated  for  various  costs  of  metal  and  costs  per  kw-hr. 
To  extend  this  table  for  costs  twice  as  great  as  those  given  in  the 
table,  multiply  the  values  in  the  table  by  1.41.  This  will  extend 
costs  up  to  40  cents  per  pound.  The  cost  per  kw-hr.  may  be  ex- 

[  508  ] 


ELECTRICAL  CALCULATIONS  Sec.  7 

tended  to  twice  the  values  in  the  table  by  dividing  by  1.41,  or  if  the 
cost  per  kw-hr.  and  per  pound  of  material  are  both  doubled,  the 
values  will  be  the  same  as  that  given  in  the  table,  i.e.  cost  of  material, 
32  cents;  cost  per  kw-hr.  6  cents.  The  ratio  of  32  to  6  is  the  same 
as  the  ratio  of  16  to  3,  therefore  K4=  2.31. 

In  Table  72,  the  values  of  K5  have  been  calculated  for  copper,  40% 
copper-covered  steel,  and  for  aluminum,  for  the  different  systems 
enumerated.  They  are  based  on  an  interest  rate  of  6%,  deprecia- 
tion rate  of  5%,  tax  rate  of  1  ^2% ;  and  for  a  continuous  use  of  energy 
for  300  days  at  8  hours  per  day,  and  they  give  a  general  indication 
of  the  economic  current  density.  However,  it  is  better  if  possible 
to  obtain  the  square  root  of  the  mean  square  load  current  over  the 
total  time  of  operation. 

I0  divided  by  this  effective  current  =  03. 
Then 

c  =  A=C3K5K4 


61.  TRANSPOSITIONS.  The  transposition  of  overhead  lines 
is  a  means  of  eliminating  mutual  inductance  between  two  circuits 
and  of  balancing  the  self-inductances  of  unsymmetrically  spaced 


Citcuir  */ 

a      a      I  a      a., 
i 

a       J a_ 


FIG.  304. 

lines.  Fig.  304  shows  a  three-phase  circuit  in  which  no  transposition 
to  equalize  the  self -inductance  of  the  wires  is  necessary.  Fig.  305 
shows  a  three-phase  circuit  in  which  it  is  necessary  to  transpose 
the  wires  as  shown  in  Fig.  306  in  order  to  equalize  the  self-inductive 
effect  in  each  wire. 

In  calculating  the  inductance  and  capacity  when  the  wires  are 
transposed  as  shown  in  Fig.  306  it  is  necessary  to  use  the  separation 
between  adjacent  wires  for  two  thirds,  and  between  outside  wires 
for  the  remaining  one-third  of  the  length  of  the  line.  With  the 
average  separation  so  determined  and  substituted  in  the  formulae 
or  table,  the  proper  value  for  the  capacity  or  inductance  is  obtained. 
It  has  also  been  shown  that  the  geometric  mean  of  these  three  dis- 
tances will  give  a  value  that  may  be  used  in  finding  inductance  and 
capacity. 

[509] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


In  Fig.  306 
di  =  12  inches, 
cb  =  24  inches. 

Then  by  the  first  method  dr: 


2x12+24 
3 


=  16 


By  the  second  method   dr  =  ^12X12X24  =  15.1 

The  first  method  has  been  longer  in  use.     The  second  method 
is  practically  new  and  was  formulated  by  J.  G.  Pertsch,  Jr. 


a   a        a   a   ft 


a  a  a 


FIG.  305. 


FIG.  306. 


[FiG.  307. 

In  Fig.  305  it  is  unnecessary  to  transpose  the  circuits  to  avoid 
mutual  inductance  if  Circuits  1  and  2  only  are  considered.  With 
Circuits  1  and  3,  however,  there  must  be  a  transposition  to  prevent 
the  effect  of  mutual  inductance.  Fig.  307  indicates  how  this  may 
be  accomplished. 

[510] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


With  two-phase  circuits  as  shown  in  Fig.  308  the  arrangement 
for  Circuit  No.  1  has  no  mutual  inductance  between  the  phases. 
The  arrangement  for  Circuit  No.  2  will  give  mutual  inductance 
between  phases  and  to  annul  this  must  be  transposed  as  shown  in 
Fig.  309.  In  Circuit  No.  3  there  is  practically  no  mutual  induc- 
tance between  the  A  and  B  phase,  but  there  is  mutual  inductance 
between  the  A  phases  of  Circuits  3  and  4,  and  the  B  phases  of  Circuits 
3  and  4;  and  each  phase  of  one  circuit  must  be  transposed  as  shown 
in  Fig.  310  to  annul  mutual  inductance.  Transpositions  must  be 


Cr*CUlT*Z 


a* 


1                                    1 

*&      t*! 

4Q                 g. 

\                                        1 

fipjutr 

*ft        ft* 

r-a    ^> 

1                                         I 

C/*CVtT 

"%a      a* 

\                                                                          \ 

\ 

FIG.  308 

y? 

>?-  

X 

FIG.  309 


A, 


a 

X 

D2 

FIG.  310 

made  between  the  generating  station  and  any  important  load  if  it 
is  desired  to  accurately  balance  inductive  effects. 

Transpositions  are  seldom  necessary  in  distribution  work  as  the 
amount  of  current  is  too  small  and  the  lengths  of  line  too  short  to 
disturb  the  voltage  relations. 

62.    CONSTANT   VOLTAGE   TRANSMISSION.     Due   to    the 

necessity  of  spacing  wires  far  apart  on  high  voltage  long  distance 

[511] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


transmission  lines,  the  reactance  is  consequently  very  large.  To 
transmit  a  large  load  and  preserve  commercial  regulation,  it  is  neces- 
sary to  have  a  comparatively  large  number  of  parallel  lines.  To 
overcome  this  difficulty  and  reduce  the  cost  of  transmission,  a  method 
is  used  consisting  of  the  installation  of  synchronous  machinery 
at  the  receiving  end,  controlled  by  automatic  voltage  relays  in  such 
manner  that  they  operate  to  vary  the  power-factor  of  the  line  with 
variation  in  load,  and  counteract  the  voltage  drop  due  to  the  load 


j 

1 

f 

4 

, 

, 

/ 

/so 

/ 

/ 

/ 

/ 

120 

SO 
60 
40 
20 
/) 

/ 

/ 

/ 

/ 

/ 

/ 

^ 

x 

/ 

i 

/ 

I 

/ 

024       6      B      /O     12     /4     /&     /&     20     22    24    26     28    30 

D/3rAWC£  IN  /AfCfffS 

FIG.  311. 

current  flowing  through  the  reactance  and  resistance  of  the  trans- 
mission line.  Installations  of  this  type  have  already  been  installed 
and  are  being  operated  very  successfully. 

63.  SPARKING  DISTANCES: 

Needle  Gaps.     There  are  many  factors  affecting  the  discharge 
voltages  of  a  needle  gap  with  a  given  separation  of  needle  points. 

,  [  512  ] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


(1)  Air  density. 

2)  Humidity. 

3)  Sharpness  of  the  needles. 

4)  Location  of  the  gap  with  respect  to  surrounding  bodies. 
(5)  Size  and  proximity  of  the  needle  supports. 

The  sparking  distances  in  inches  and  centimeters  in  air  between 
Sharp  No.  6  opposed  needle  points  for  various  effective  sinusoidal 
voltages  are  given  in  Table  73  and  Fig.  311. 

This  table  and  curve  are  approximately  correct  for  the  following 
conditions: 

A  barometric  pressure  of  29.92  inches  of  mercury,  a  temperature 
of  77°  F.  and  about  (75-80)  per  cent  humidity,  which  are  average 
conditions. 

A  non-inductive  resitance  of  about  %  to  4  ohms  per  volt  should 
be  inserted  in  series  with  the  gap. 

No  extraneous  body  should  be  nearer  the  gap  than  a  radius  of 
twice  the  gap  length.  It  is  not  good  practice  to  use  the  needle  gap 
for  voltages  above  100  kv. 

The  Sphere  Gap,  discharge  voltage  is  affected  by  fewer  variables 
than  the  needle  gap. 


_     TABLE  73 

SPARKING  DISTANCES 

NEEDLE  POINTS 

DISTANCE 

DISTANCE 

Kilovolts 

Kilovolts 

R.  M.  S. 

R.  M.  S. 

Inches 

Cm. 

Inches 

Cm. 

5 

0.225 

0.57 

140 

13.95 

35.4 

10 

0.47 

1.19 

150 

15.0 

38.1 

15 

0.725 

1.84 

160 

16.05 

40.7 

20 

1.0 

2.54 

170 

.17.10 

43.4 

25 

1.3 

3.3 

180 

18.15 

46.1 

30 

1.625 

4.1 

190 

19.20 

48.8 

35 

2.0 

5.1 

200 

20.25 

51.4 

40 

2.45 

6.2 

210 

21.30 

54.1 

45 

2.95 

7.5 

220 

22.35 

56.8 

50 

3.55 

9.0 

230 

23.40 

59.4 

60 

4.65 

11.8 

240 

24.45 

62.1 

70 

5.85 

14.9 

250 

25.50 

64.7 

80 

7.1 

18.0 

260 

26.50 

67.3 

90 

8.35 

21.2 

270 

27.50 

69.8 

100 

9.6 

24.4 

280 

28.50 

72.4 

110 

10.75 

27.3 

290 

29.50 

74.9 

120 

11.85 

30.1 

300 

30.50 

77.4 

130 

12.90 

32.8 

17 


[513] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


(1)  Air  density. 

(2)  Location  of  the  gap  with  respect  to  surrounding  bodies. 

(3)  Size  of  the  gap  supports. 

In  spheres  larger  than  10  cm.  in  diameter  the  third  item  noted 
above  is  practically  negligible. 

The  sparking  distances  in  inches  and  centimeters  in  air  between 
different  size  spheres  for  various  effective  sinusoidal  voltages  will 
be  found  in  Tables  74  to  76  and  Figs.  312  and  313. 

These  tables  and  curves  are  correct  for  a  barometric  pressure  of 
29.92  inches  of  mercury  and  a  temperature  of  77°  F.  No  data  are 
at  present  available  for  sphere  gap  corrections,  but  at  or  near  sea 
level,  corrections  for  variation  in  barometric  pressure  and  temperature 
may  be  made  by  multiplying  the  values  in  the  table  by 

17.91  b 
459 +t 
in  which        b  =  barometric  pressure  in  inches  of  mercury. 

and  t  =  temperature  in  degrees  fahrenheit. 
A  non-inductive  resistance  of  about  ^  to  4  ohms  per  volt  should 
be  inserted  in  series  with  the  gap.  No  extraneous  body  should  be 
nearer  the  gap  than  a  radius  of  twice  the  gap  length.  It  has  been 
suggested  that  for  most  commercial  testing,  needle  gaps  may  be 
used  up  to  about  60,000  volts  and  sphere  gaps  from  about  50,000 
up  to  the  highest  voltages  now  used. 


TABLE  74 

SPHERE  GAP  SPARK-OVER  VOLTAGES 

12.5  cm.  SPHERES 

[SPACING 

KILOVOLTS  EFFECTIVE 

Cm. 

In. 

Non-Grounded 

Grounded 

0.25 

0.098 

6.5 

6.5 

0.50 

0.197 

12 

12 

1 

0.394 

22 

22 

1.5 

0.591 

31.5. 

31.5 

2 

0.787 

41 

41 

3 

1.181 

59 

59 

4 

1.575 

76 

75 

5 

1.969 

91 

89 

6 

2.362 

105 

102 

7 

2.756 

118 

112 

8 

3.150 

130 

120 

9 

3.543 

141 

128 

10 

3.937 

151 

135 

12 

4.72 

167 

147 

15 

5.91 

188 

160 

17.5 

6.88 

201 

168 

20 

7.87 

213 

174 

[514] 


ELECTRICAL  CALCULATIONS 


Sec.  7 


TABLE  75 

SPHERE  GAP  SPARK-OVER  VOLTAGES 
25  cm.  SPHERE 


SPACING 

KILOVOLTS  EFFECTIVE 

Cm. 

In. 

Non-Grounded 

Grounded 

0.5 

0.197 

11 

11 

1 

0.394 

22 

22 

1.5 

0.591 

32 

32 

2 

0.787 

42 

42 

2.5 

0.983 

52 

52 

3 

1.181 

61 

61 

4 

1.575 

78- 

78 

5 

1.969 

96 

94 

6 

2.362 

112 

110 

7.5 

2.953 

135 

132 

10 

3.937 

171 

166 

12.5 

4.92 

203 

196 

15 

5.91 

230 

220 

17.5 

6.88 

255 

238 

20 

7.87 

278 

254 

22.5 

8.85 

297 

268 

25 

9.83 

314 

280 

30 

11.81 

339 

300 

40 

15.75 

385 

325 

TABLE  76 

SPHERE  GAP  SPARK-OVER  VOLTAGES 
50  cm.  SPHERES 


SPACING 

KILOVOLTS  EFFECTIVE 

Cm. 

In. 

Grounded  Values 

2 

0.787 

40 

4 

1.575 

76 

6 

2.362 

112 

8 

3.150 

145      H  ] 

10 

3.937 

185 

12 

4.72 

220 

14 

5.50 

250 

16 

6.28 

275 

18 

7.07 

300 

20 

7.87 

320 

22 

8.65 

345 

[  515  ] 


Sec.  7 


ELECTRICAL  CALCULATIONS 


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[516] 


ELECTRICAL  CALCULATIONS  Sec.  7 


BIBLIOGRAPHY 

American  Electrician's  Handbook. 
Foster's  Electrical  Engineer's  Pocketbook. 
Standard  Handbook  for  Electrical  Engineers. 
Electrical  Appendix  D'Este's  Steam  Engineer's  Manual. 
Franklin  &  Williamson's  Alternating  Current. 
Calculations  of  Alternating  Current  Problems.     (Cohen.) 
Overhead  Electric  Power  Transmission.     (Still.) 
Proceedings  A.  I.  E.  E. 

Corona  F.  W.  Peek,  Jr.,  July  1911,  June  1912,  June  1913. 
Transmission  Calculation. 

Transmission  Calculation    (Fender),  June  1908,  July  1911. 

Transmission  Calculation  (Thomas),  June  1909. 

Transmission  Calculation  (Kennelly),  Dec.  1911,  June  1912. 

Transmission  Calculation  (Dwight),  June  1913. 
U.  S.  Weather  Bureau. 
Electric  Journal,  1905,  1906. 
General  Electric  Review,  1912. 
General  Electric  Review,  1913. 


[617] 


SECTION  8 

MECHANICAL  CALCULATION  OF  TRANS- 
MISSION AND  DISTRIBUTION  LINES 


SECTION  8 

MECHANICAL  CALCULATIONS  OF  TRANSMISSION  AND 
DISTRIBUTION  LINES 


TABLE  OF  CONTENTS 

ARTICLE 

General 1 

Fundamental  formulae 

Wind  pressure 2 

Compression  and  tension 3 

Shearing  stress 4 

Bending  moment 5 

Torsion 6 

Strength  of  timber Table  77 

Moment  of  inertia  and  section  modulus Table  78 

Bending  moment Table  79 

Solution  of  sag  problems 

General 7 

Weight  of  wire 8 

Weight  of  wire  and  ice 9 

Wind  pressure 10 

Resultant  load  of  ice  and  wind  pressure 11 

Temperature  changes 12 

Symbols  and  formulae 13 

Problems 14 

Loading,  sag  and  length  Tables 

Cross-arms 

General 15 

Bending  moment  due  to  weight  of  wires 16 

Bending  moment  due  to  unbalance  tension  in  wires 17 

Pole  stresses . 18 

Wind  pressure  on  pole  and  conductor 19 

Dead  end  loading 20 

Bends  in  line 21 

Guying 22 

Concrete  and  Steel  Structures 23 

[521] 


1.  GENERAL.     The  mechanical  problems  met  with  in  the  design 
of  a  transmission  line  can  in  general  be  divided  into  two  classes: 

(a)  Stresses  incident  to  the  plan  of  a  line, 

(b)  Stresses  which  occur  due  to  changes  in  temperature  and  to 
abnormal  weather  conditions. 

The  stresses  incident  to  the  design  of  a  line  are  those  which  occur 
at  dead  ends  and  at  bends  in  the  line. 

The  stresses  which  occur  due  to  changes  in  temperature  and  to 
wind  and  ice  loads  must  be  assumed  and  vary  with  local  conditions. 

The  solutions  of  the  mechanical  problems  involved  entail  the 
application  of  fundamental  formulae  whicfi  formulae  are  listed  below. 

The  problems  solved  herein  have  been  calculated  on  the  slide 
rule  wherever  possible,  which  method  is  suggested  as  being  suffi- 
ciently accurate  since  variations  in  material  will  more  than  offset 
any  error  incident  to  slide  rule  calculation. 

FUNDAMENTAL  FORMULA 

2.  Wind  Pressure  Formulae. 

V    =  actuel  velocity  of  wind  in  miles  per  hour. 
F    =  pressure  in  pounds  per  square  foot. 
B    =  barometric  pressure  in  inches. 
Then  for  small  flat  surfaces. 

F    =  0.004  X^rX  V2 

~.       -~~ 
For  the  projected  surface  of  a  cylinder  (diameter  X  length). 

F    =  0.0025  V2 

3.  Compression  and  Tension  Formulae. 

s     =  tension  or  compression  stress  in  pounds  per  square  inch. 
a     =  area  in  square  inches  at  right  angle  to  the  direction  of  the 

force  producing  the  stress. 
\Vt  =  total  weight  or  force  in  pounds  producing  tension  or  com- 

pression stresses. 


4.  Shearing  Stress  Formula. 

s     =  shearing  stress  in  fibre  in  pounds  per  square  inch. 
a     =  area  in  square  inches  parallel  to  shearing  force. 
Wt  =  total  weight  or  force  in  pounds  producing  shear. 

Then  s  =  Ei 

5.  Bending  Moment  Formulae. 

M  =  bending  moment  in  pound-inches. 
s     =  maximum  fibre  stress  per  square  inch. 

[  523  ] 


Sec.  8 
c 


MECHANICAL  CALCULATIONS 


distance  from  neutral  axis  to  point  of  maximum  fibre 
stress. 

I     =  moment  of  inertia. 
Q    =  section  modulus. 


6.  Torsion  Formulae. 

Mt=  torsion  moment  in  pound-inches. 

s     =  maximum  shearing  stress  per  square  inch. 

c     =  distance  in  inches  from  neutral  axis  to  point  of  maximum 

fibre  stress. 

J     =  polar  moment  of  inertia. 
Ii    =  least    reactangular   moment  of  inertia  about  two  axes 

passing  through  the  centre. 
I;    =  greatest  reactangular  moment  of  inertia  about  two  axes 

passing  through  the  centre. 

TV/T       sj 
Mt-  — 


7.  SOLUTION  OF  SAG  PROBLEMS. 

The  sag  necessary  in  any  span  is  dependent  upon  the  following: 
a.  The  character  and  size  of  the  conductor  (Art.  8). 


TABLE  77 

STRENGTH  OF  TIMBER 

In  Ibs.  per  sc[.  in. 

Untreated  Timber 

Bending 

Compression 

Port  Orford  Cedar 

6900 

(69001         L    ^ 

Long  Leaf  Yellow  Pine  

6000 

6000 

White  Oak                                       .    . 

5700 

5700 

Douglas  Fir     

5400 

5400 

5100 

5100 

Washington  Cedar  

5100 
5100 

5100 
5100 

Idaho  Cedar          

Short  Leaf  Yellow  Pine                           

4800 

4800 

Bald  Cypress  (heartwood)                 

4800 

4800 

Red  Cedar 

4200 

4200 

Redwood                                                     

3900 

3900 

Eastern  White  Cedar 

3600 

3600 

Juniper                                                            

3300 

3300 

Catalpa  

3000 

3000 

L  =  Length  in  inches. 

D  =  Least  side,  or  diameter,  in  inches. 

[  524  ] 


MECHANICAL  CALCULATIONS 


Sec.  8 


TABLE  78 

Shape  of  Section 

Moment  of 
Inertia 
I 

Section 
Modulus 
Q 

Sq.  Least  Radius 
of  Gyration 

d4 
12 

fed3 
12 

~l2~ 

6d3-6'd'3 

d3 

6 

6d2 
6 

I 

7 

d2 
12* 

12 

m 

''ff 

•f 
J 

1 

^$%$$$& 

| 

!-f- 

12 

7 

%%%%%j 

• 

X       wr*  ^ 

"_t] 

12 

.0491  (d4-d/4) 
bd?-2b'd'3 

.5d 

^,  or  .0982  d3 

oZ 

0982^3^ 

A 

d2 
16 

d2+d'2 

* 

-of? 

HI 

B 

OQ 

x  w5T 

\        d  f 

\>           j 

i 

16 

7 

—  , 

X  1  X'>s 

xTrJ 

12 

Ad2,. 
^g(Approx.) 

Ad2 

0.5  d 
^  (Approx.) 
Ad  (. 

A 

7 
A 

7 

J: 

-A  ^5 

7.34 

),Q  I 

A 

NOTE. — A  =  total  area  of  section.  In  calculating  the  least  radius  of  gyration  be 
sure  to  use  the  least  moment  of  inertia,  x  x'  denotes  the  neutral  axis,  and  the 
value  of  /  given  ia  that  about  this  axis. 

[525] 


Sec.  8 


MECHANICAL  CALCULATIONS 


TABLE  79 


Method  of  Loading 


Maximum  Bending 

Moment 

M. 


Maxi- 
mum 
Load 
W 


Deflection 
D. 


Length  in 
Feet 


Load  in 
Pounds 


Ft.-Lb. 


In.-Lb. 


Lb. 


In. 


W  L 


W  L 
6 


W  L 
2 

WL 

~T~~ 

W  A 
2 

W  A 


3W  L 


2W  L 


QW  L 


12  W  L 


3W  L 


6  W  A 


QW  A 


2QS 
3L 


QS 
2L 


QS 
6L 


12  L 


QS 
3L 


SA 
6A 


QS 
QA 


384  E  I 


WP 
WEI 


SE  I 


WP 
3E  1 


Wl3 
48  El 


48  E  I 
(3  /2-4  a2) 
Between 
Supports. 
Wa 
1QE~I* 
(1-2  a)2 


L—  length  in  feet;  1= length  in  inches;  W= total  load  in  pounds;  E— modulus 
of  elasticity;  7= moment  of  inertia;  Q  =  section  modulus;  S=safe  stress  on  the 
extreme  fibres  of  the  beam  section (  =  modulus  of  rupture -r-fector  of  safety).  In 
figuring  deflections,  all  lengths  must  be  expressed  in  inches;  and  small  letters  I,  a, 
and  6  are  used  as  reminders. 

[  526] 


MECHANICAL  CALCULATIONS  Sec.  8 

b.  The  maximum  load  to  which  it  will  be  subjected  (Art.  9. 

10,  11). 

(Weight  of  wire  plus  ice  and  wind  load.) 

c.  Maximum  variation  in  temperature  (Art.  12). 

8.  The  Weight  of  the  Wire  depends  upon  — 
The  material. 

The  area  of  cross-section. 
Whether  solid  or  stranded. 
Whether  insulated  or  bare. 

The  weight  of  conductor  per  foot  may  be  found  in  Tables  80  to  85, 
Sec.  8,  and  per  1000  feet  in  Tables  33  and  34,  Sec.  3. 

9.  Weight  of  Wire  and  Ice.     (Tables  80  to  85.) 
d     =  diameter  of  wire  in  inches. 

t     =  thickness  of  ice  in  inches  (assuming  a  cylindrical  forma- 

tion). 

W  =  weight  of  wire  in  pounds  per  foot. 
Wt=  total  weight  of  wire  and  ice  in  pounds  per  foot  of  con- 

ductor (assuming  ice  weighs  57.2  Ibs.  per  cu.  ft.). 

Wt=  W+1.248  (dt+t2). 

10.  Wind  Pressure  on  Wires.     (Tables  80  to  85.) 
F    =  wind  pressure  in  pounds  per  square  foot. 

d     =  diameter  of  wire  in  inches. 
t     =  thickness  of  ice  in  inches. 
Fo  =  force  in  pounds  per  foot  length  of  wire. 
For  wire  alone 


For  wire  and  ice 

_,      F  (d+2t) 
~12~ 

11.  Total  Resultant  Load  produced  by  the  weight  of  the  wire 
plus  the  wind  and  ice  loads. 

FO  =  horizontal  force  in  pounds  per  foot  length  of  wire. 
Wt  =  the  total  weight  or  the  vertical  force'  in  pounds  per  foot 
length  of  wire. 


This  may  also  be  solved  trigonometrically  (Fig.  314)  as  follows: 

W-    W< 

~  . 


FIG.  314. 
[  527  1 


Sec.  8  MECHANICAL  CALCULATIONS 

12.  Temperature  Changes.     Changes  in  temperature  affect  the 
solution  of  the  sag  problems  in  that  the  total  length  of  wire,  and 
therefore  the  sag  increases  and  decreases  with  increasing  and  de- 
creasing temperature. 

13.  Symbols  and  Formulae.     The  resultant  sag  is  determined  by 
combining  all  the  above  factors  in  one  solution,  the  formulae  for  which 
follow : 

These  formulae  in  connection  with  the  curves  in  Figs.  318  to  320 
may  be  used  to  solve  the  mechanical  problems  met  with  in  the  *• 
stringing  of  conductors. 

The  curves  Figs.  318  to  320  are  illustrated  on  a  very  small  scale 
and  for  calculations  should  be  increased  in  size. 

The  data  necessary  for  the  preparation  of  these  curves  are  given 
in  Table  86,  from  which  table  curves  of  sufficient  size  to  obtain 
accurate  results  may  be  plotted. 

D   =  distance  in  feet  between  supports. 

d    =  sag  in  feet  at  stringing  temperature  "t." 

t     =  stringing  temperature  in  Degrees  F. 

T    =  total  tension  in  the  wire  in  pounds  at  temperature  "t." 

s     =  stress  per  square  inch  at  tension  "T." 

a     =  effective  area  of  wire  in  square  inches. 

W  =  weight  per  foot  of  wire. 

di   =  sag  in  feet  at  desired  change  in  temperature  or  tempera- 
ture at  maximum  stress. 

ti    =  temperature  at  which  stress  is  desired,  or  temperature  at 
maximum  stress. 

Ti  =  tension  in  wire  in  pounds  at  temperature  ti. 

Si    =  stress  per  square  inch  at  tension  TI. 

Wi  =  weight  of  loaded  wire  (includes  ice  load  or  ice  and  wind 
load). 

a     =  co-efficient  of  linear  expansion  per  degree  F. 

E    =  modulus  of  elasticity. 

r 
_  length  of  wire  at  temp,  (t) 

~D~ 

length  of  wire  at  temp,  (ti) 
11  nD- 

length  of  wire  at  temp,  (t) 


.  ,       unstressed  length  of  wire  at  temp. 
— D — 

X=f 

Xi    =  -jj- 

[52SJ 


K  =    sa 


WD 

si  a 


MECHANICAL  CALCULATIONS  Sec.  8 


f°r  change  in  temperature  only. 


o     fl, 

KI  =  YT^-J}     for  change  in  temperature  and  in  load. 

T    =  sa 
Ti  =  si  a 

When  wire  loading  is  unchanged,  but  temperature  is  changed. 

Then 

lo    =   I--1- 

V    =    lo-o  (t-ti) 

When  conditions  are  given  at  heavy  loading  in  order  to  find  con- 
ditions at  light  loading. 


Wl 

lo     =    lo'  +  a  (t-ti) 

When  conditions  are  given  at  light  loading  in  order  to  find  con- 
ditions at  heavy  loading. 


lo'    =    lo-a  (t-ti) 

When  the  supports  for  the  wire  are  at  different  levels,  the  distance 
from  the  higher  support  to  the  lowest  point  of  the  wire  in  the  span  is 
determined  and  the  problem  solved  for  a  span  twice  the  length  of  the 
distance  so  determined. 

Xi    =  distance  in  feet  from  the  lowest  point  in  the  span  to  the 

higher  support. 

h    =  difference  in  level  in  feet  between  the  wire  supports 
d    =  sag  in  feet  measured  from  the  higher  support. 
D   =  the  horizontal  distance  in  feet  between  wire  supports. 

x  =  D    I  hsa=  D   [  Kh 

[529] 


Sec.  8  MECHANICAL  CALCULATIONS 

also 


When  Xi  has  been  determined,  solve  the  problem  as  though  fo\ 
level  wire  supports,  but  for  a  length  of  span  equal  to  the  corrected 
length  DI,  where 


14.  PROBLEMS: 

Problem  1.  Determine  the  change  in  the  sag  and  in  the  tension 
of  the  conductor  due  to  a  drop  in  temperature  to  10°  F.  when 
strung  under  the  following  conditions  : 

Length  of  span  200  feet. 

Sag  at  stringing  temperature  1.5  feet. 

Stringing  temperature  70°  F. 

Conductor  —  Bare,  Hard  drawn,  Stranded  No.  00  Copper  wire. 

D  =  200  feet. 

d  =1.5  feet. 

t  =  70°  F. 

ti  =  10°  F. 

W  =  0.406.     (From  Table  82.) 

a  =  0.1045.     (From  Table  82.) 

E  =  16,000,000.     (From  Table  81.) 

a  =  0.0000096.     (From  Table  81.) 

Solution: 


In  Fig.  315  lay  off  X  a  parallel  to  oy.  Draw  Kc  parallel  to  ox  and 
through  the  intersection  b  of  X  a  and  the  sag  curve. 

Drop  a  perpendicular  line  dl  from  the  intersection  d  of  Kc  and  the 
length  curve. 

K  =  16.3 
1  =  1.000156 

KWD     16.3X0.406X200 


0.1045 


=  12,600  Ibs.  per  sq.  inch. 


1  -        =  ,.0001»--  =  0.9993645 


Lay  off  the  difference  between  1  and  10  (Fig.  315)  =1  -0.9993645 
0.0006355,  from  O. 

Draw  a  line  from  10  through   d. 


[  530] 


MECHANICAL  CALCULATIONS  Sec.  8 


[531] 


Sec.  8  MECHANICAL  CALCULATIONS 

V  =  0.9993645-  0.0000096  (70  -  10) 
V  =  0.9993645  -  0.000576  =  0.9987885 

Lay  off  the  difference  between  1  and  1'0.  =  1  -  0.9987885  =  0.00121 15 
from  O  and  draw  10  e  parallel  to  10  d  intersecting  the  length  curve  at 
f .  Draw  Kig  through  f  parallel  to  ox  and  where  it  intersects  the  sag 
curve  h,  drop  a  perpendicular  Xih 

Then 

Ki  =  24.3 
Xi    =  0.0051 
From  which 
Ti  =  K!  VV  D  =  24.3  X  0.406  X 200  =  1,975  Ibs. 

KtWD     24.3X0.406X200 

81  =  ""-T~  -01045-       =  18'9°°  lbs  Per  Sq'  m' 

di  =  \!  D  =  0.0051  X  200  =  1.02  feet. 
di=  1.02X12  =  12.24  inches. 

Problem  2.  Determine  the  sag  and  the  tension  of  the  conductor 
when  strung  at  a  temperature  of  70°  F.,  so  that  when  subjected  to  a 
temperature  of  0°  F.  and  the  additional  load  of  }/2  of  sleet,  and  a 
wind  pressure  of  8  lbs.  per  square  foot,  the  stress  in  the  conductor 
will  be  within  17,000  lbs.  per  square  inch,  for  the  following  structural 
conditions: 

Length  of  span  200  feet. 

Conductor — Triple  Braid  Weatherproof,  soft  drawn  solid  No.  00 
copper  wire. 

D   =  200  feet, 
t     =  70°  F. 
ti    =  0°  F. 

Wi=  1.518.     (Table  84.) 
W  =  0.502.     (Table  84.) 
a     =0.1045.    -  (Table  84.) 
E    =  12,000,000.     (Table  81.) 
a     =  0.0000096.     (Table  81.) 
s     =  17,000  lbs. 

Solution  : 

„  _  BI&  _  17,000  X0.1045_gog 
~WiD~     1.518X200 

In  Fig.  316  draw  Ki  a  parallel  to  ox,  where  this  line  intersects  the 
length  curve  at  a  drop  a  perpendicular  line  a  li  and  obtain  li 
li    =  1.001225 

T       i       Sl      1  nmo9*        17,000 
lo=l1— E-  =  L001225-12,000,000 
To  =  0.999809. 

[  532] 


MECHANICAL  CALCULATIONS 


Sec.  8 


Sec.  8  MECHANICAL  CALCULATIONS 

Lay  off  the  difference  between  1  and  1'0  =1-0.999809=0.000191 
from  0. 

0502\ 


1'  =  1.000279 

Lay  off  1'  from  0  and  erect  a  perpendicular  intersecting  Ki  a  at  b, 
draw  roc  through  1'0  and  b. 

lo  =  I'o  +    a(t-ti) 

10  =  0.999809+0.0000096  (70-0)  =0.999809+0.000672 
10  =  1.000481 

Lay  off  10  from  0  and  draw  I0d  parallel  to  l'0c  intersecting  the 
length  curve  at  c.  Draw  Kf  parallel  to  ox  through  e  and  where  Kf 
intersects  the  sag  curve  at  g,  drop  a  perpendicular  gX. 

X     =  .0194 
K   =  6.475 

d    =  XD  =  0.0194X200  =3.88  ft. 
d    =  3.88X12  =  46.56  inches 
T    =  K  W  D  =  6.475X0.502X200  =  650  Ibs. 
KWD       650 


0.1045 


=  6210  Ibs.  per  square  inch. 


Problem  3.  Determine  the  sag  and  tension  of  a  conductor  at  10° 
F.  when  loaded  with  Yz'  of  sleet  and  a  wind  pressure  of  8  Ibs.  p°r 
square  foot  for  the  following  structural  conditions. 

Length  of  spans  200  feet. 

Conductor — Bare,  stranded  No.  00  aluminum  wire. 

Stringing  temperature  70°  F. 

Sag  4.5  feet. 

D   =200  feet. 

d     =  4.5  feet. 

t     =  70°  F. 

ti    =  10°  F. 

W  =  0.122.     (From  Table  85.) 

Wi  =  1.168.     (From  Table  85.) 

a     =  0.1045.     (From  Table  85.) 

E    =9,000,000.     (From  Table  81.) 

a     =0.0000128.     (From  Table  81.) 

Solution: 

d      4.5 

D      200  Continued  on  page  545. 

[  534  1  ' 


MECHANICAL  CALCULATIONS 


Sec.  8 


9 


[535J 


Sec.  8 


MECHANICAL  CALCULATIONS 


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[536] 


MECHANICAL  CALCULATIONS 


Sec.  8 


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[537] 


Sec.  8 


MECHANICAL  CALCULATIONS 


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[  538  ] 


MECHANICAL  CALCULATIONS 


Sec.  8 


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[539] 


Sec.  8 


MECHANICAL  CALCULATIONS 


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[540] 


MECHANICAL  CALCULATIONS 


Sec.  8 


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[541] 


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Sec.  8 


MECHANICAL  CALCULATIONS 


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[542] 


MECHANICAL  CALCULATIONS 


Sec.  8 


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.01 


.02 


FIG.  319. — Relation  between,  length  and  sag  per  foot  of  span,  and  total  stress  in 
conductor  per  pound  of  conductor  one  foot  long. 


[543] 


Sec.  8 


MECHANICAL  CALCULATIONS 


/ 

/ 


7 


MECHANICAL  CALCULATIONS 


Sec.  8 


TABLE  86 

DATA  FOR  PLOTTING  LENGTH  AND  SAG  CURVES 

1 

X 

k 

1.0000042 
1.0000051 
1.0000061 
1.0000071 
1.0000082 

0.00125 
0.00138 
0.00150 
0.00162 
0.00175 

100.0013 
90.9105 
83,3348 
76.9247 
71.4303 

1.0000094 
1.0000107 
1.0000118 
1.0000136 
1.0000151 

0.00188 
0.00200 
0.00212 
0.00225 
0.00238 

66.6685 
62.5020 
58.8257 
55.5578 
52.6339 

1.0000167 
1.0000261 
1.0000372 
1.0000511 
1.0000667 

0.00250 
0.00313 
0.00375 
0.00438 
0.00500 

50.0025 
40.0031 
33.3371 
28.5758 
25.0050 

1.000104 
1.000150 
1.000266 
1.000417 
1.000598 

0.00625 
0.00730 
0.01000 
0.01250 
0.01500 

20.0063 
16.6742 
12.5100 
10.0125 
8.3483 

1.000817 
1.001066 
1.001351 
1.001668 
1.002017 

0.01751 
0.02001 
0.02252 
0.02502 
0.02753 

7.1604 
6.2700 
5.5781 
5.0250 
4.5730 

1.002402 
1.003754 
1.006680 
1.010444 
1.015068 

0.03004 
0.03757 
0.05017 
0.06283 
0.07556 

4.1967 
3.3709 
2.5502 
2.0628 
1.7422 

1.020542 
1.026881 
1.034093 
1.042191 
1.051185 

0.08840 
0.10134 
0.11441 
0.12763 
0.1410U 

1.5170 
1.3513 
1.2255 
1.1276 
1.0501 

1.061089 
1.083691 

0.15455 
0.18226 

0.9879 
0.8965 

Draw  X  a  parallel  to  oy  and  intersecting  sag  curve  at  b ;  draw  Kc 
through  b  parallel  to  ox  and  intersecting  length  curve  at  d.  Drop 
a  perpendicular  dl.  (Fig.  317.) 

K   =  5.6. 

1     =  1.00134 

KWD     5.6X0.122X200     10__  1U  .     -, 

=  1308  IDS.  per  square  inch. 


0.1045 


18 


[545] 


Sec.  8 


MECHANICAL  CALCULATIONS 

1308 


=  1.0011947. 


Lay  off  10  from  0. 


1'  =  1.002586. 

Lay  off  1'  from  0  and  draw  l'e  parallel  to  oy,  intersecting  Kc  at  f. 
Draw  log  through  f  . 

I'o    =  lo  -  a(t-ti)=  1.0011947  -0.0000128  (70  -10)  = 
1'0   =  1.0004267.' 

Lay  off  I'o  from  0  and  draw  1'0  h  parallel  to  I0g  intersecting  the 
length  curve  at  i;  draw  a  line  KJ  parallel  to  ox  through  i  and  inter- 
secting the  sag  curve  at  m,  drop  a  perpendicular  line  Xim  from  m. 

Xi    =  0.02515. 
Ki  =  5.025. 
Then 

Ti  =Ki  Wi  D=5.025X1.168X200  =  1176  pounds. 

6i  =  KlWlD  ^L1!??;!  =  11,230  pounds  per  square  inch. 

£L  pJ.J.U4O 

dj   =  XiD=0.02515X200  =  5.03  feet. 
di  =  5.03X12  =60.36  inches. 


CROSS-ARMS 

15.  General.    The  ordinary  stresses  on  cross-arms  may  be  divided 
into  two  classes. 

1.  The  stress  produced  by  the  bending  moment  caused  by  the 
weight  of  the  wires.     (Vertical.)     (Art.  16.) 


j 

h      * 

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*        1 
*         i 

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3       *> 

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*S        Vi 

\  \ 

17 

| 

1 

1 

* 
_    X 

m  y 

L-4- 

—  ^ 

,  l_  y  _f. 

** 

*.g                                            |       -    -       |                                             «c7 

Fia.  321. 
[546] 

MECHANICAL  CALCULATIONS  Sec.  8 

2.  The  stress  produced  by  the  bending  moment  caused  by  an 

unbalanced  tension  of  the  wires.     (Horizontal.)     (Art.  17.) 
The  solution  of  problems  to  determine  the  following  stresses  has 
not  been  included  for  the  reasons  outlined  below,  although  in  some 
cases  they  may  be  of  importance. 

1.  Shear  and  compression,  as  calculations  indicate  that  such 

stresses  in  cross-arms  are  negligible. 

2.  Torsion,  since  the  bending  of  the  cross-arm  renders  calculated 

stress  values  very  unreliable. 

3.  Torsion  on  poles  and  cross-arms  due  to  broken  wires  as  the 

relative  flexibility  of  the  pole  will  introduce  an  error  of 
approximately  50%  in  the  calculated  results. 

16.  Bending  Moment  Due  to  the  Weight  of  the  Conductor.    (Fig. 
321.) 

Let 

DI  &  D2  =  length  of  adjacent  spans  in  ft. 

Tu  =  the  unbalanced  tension  in  the  conductor  in  Ibs. 

li,  12,  la  etc.  =the  lever  arm  or  distance  from  the  center  of  the 

pole  to  the  center  of  the  pins  in  inches. 
1     =  the  distance  between  pins  in  inches  (assuming  the  distance 

from  the  center  of  the  pole  to  the  pole  pin  equals  1). 
Wti,  Wt2,  Wts,  etc.  =the  total  weight  of  the  respective  conductors 

supported  by  the  pins, 
n     =  the  number  of  pins  in  the  cross-arm. 
M  =  the  bending  moment  in  pound-inches. 

Then 

M   =  (Wti  ll+Wta  Is  +Wt5  Is  + +Wtn-!  In-i) 

or 

M    =   (Wt2  l2+Wt4   U  +  WtPl6  + +Wtn  In). 

The  above  formula)  are  simplified  when  all  the  wires  have  the  same 
weight,  then — 

M  =  Wtl  1 


Problem:  Find  the  fiber  stress  in  pounds  per  square  inch  in  a  six 
pin,  8  ft,  3J/2  x  4^  standard  cross-arm,  each  pin  supporting  a  No.  00 
stranded  bare  copper  wire,  with  the  additional  load  of  Y^'  covering 
of  ice;  assuming  200  ft.  spans. 

Solution : 

From  Table  82. 
Wt  =   0.978. 


F547] 


Sec.  8  MECHANICAL  CALCULATIONS 

(Di+D«)Wt 


400X0.978 

—  —  =  195.6  Ibs. 


i 

M    =    195.6X14.5(1+2+3). 

M    =    195.6  X  14.5X6  =  17,020  Ibs.-inches. 

s      =   Fiber  stress. 

6=ra     Table  78- 

b      =   Dimensions  of  cross-arm  in  inches  at  90°  to  force. 
d      =   dimensions  of  cross-arm  in  inches  parallel  to  force. 

6X17,020 

8      =  o  t-^fA  Kxo  =  M43  lbs-  Per  square  inch. 

O.O  A.  (^t.O) 

The  weight  of  the  insulators  and  ice  on  the  cross-arm,  the  reduc- 
tion in  cross-section  due  to  the  bolt  holes,  and  the  supporting  effect 
of  the  braces  have  not  been  considered  as  they  effect  the  result  by 
less  than  5%  and  are  generally  covered  by  the  factors  of  safety  used. 

17.  Bending  Moment  Due  to  the  Unbalanced  Tension  in  Con- 
ductors exemplified  by  dead  ending  the  line. 

Problem: 

Find  the  fiber  stress  in  pounds  per  square  inch  in  each  of  two  4- 
pin  5  ft.  7  inches,  3^"  x  4  Hi"  standard  cross-arms  and  supporting 
through  pin  type  insulators  to  each  of  which  is  attached  a  No.  00 
hard-drawn  stranded  bare  copper  wire. 

Solution: 

If  a  through  pin  type  insulator  is  used  on  two  arms  and  consider- 
ing the  wire  stress  Tu  =  1,975  Ibs.  (From  Art.  14.) 

Then 

M  =  1,975X14.5  (1+2)  =86,000  Ibs.  inches  for  two  arms. 
M  =43,000  Ibs.  inches  for  one  arm. 
6X43,000 


45X(35)2 


4,675  Ibs.  per  square  inch. 


Double  arms,  as  generally  used,  to  which  wires  are  connected  to 
insulators  in  tandem,  complicate  the  problem  in  that  a  form  of  canti- 
lever truss  is  thereby  produced. 

In  the  solution  of  such  problems,  the  load  is  divided  by  two  and 
the  fiber  stress  for  a  single  arm  is  calculated.  This  solution  assumes 


548 


MECHANICAL  CALCULATIONS  Sec.  8 

that  the  load  is  equally  divided  between  the  two  cross-arms  and  neg- 
lects the  truss  effect. 

18.  POLE  STRESSES 
Forces  Producing  Pole  Stresses. 

Wind  pressure  on  the  pole.     (Art  19.) 
Wind  pressure  on  the  conductors.     (Art.  19.) 
Unbalanced  wire  tension. 

a — Dead  ends.     (Art  20.) 

b — Bends  in  a  line.     (Art.  21.) 

19.  Wind  Pressure  on  Pole  and  Conductors. 
Symbols: 

F     =   the  wind  pressure  in  pounds  per  sq.  ft.  of  projected  area 

of  pole  or  wires  (Art.  2). 

FO    =   the  wind  pressure  in  Ibs.  per  ft.  length  of  wire.     (Art.  10.) 
s      =   the  fiber  stress  of  pole  in  Ibs.  per  square  inch. 
H     =   the  height  of  pole  in  feet  above  ground, 
di     =   the  diameter  of  pole  at  ground  in  inches. 
d2    =   the  diameter  of  pole  at  top  in  inches. 
d3     =  the  diameter  of  pole  where  effect  of  load  is  applied. 
DI  &  D2  =  the  adjacent  spans  in  feet, 
ni     =   the  number  of  wires  at  dist.  LI  from  ground. 
n2    =   the  number  of  wires  at  dist.  L2  from  ground. 
L     =   the  effective  lever  arm  in  feet. 
Pp  =   the  total  wind  pressure  on  pole. 
PCI  =   the  total  wind  pressure  on  wires  LI  feet  from  ground. 
PC2  =   the  total  wind  pressure  on  wires  L2  feet  from  ground. 
Mp  =   the  bending  moment  of  pole. 

MCI  =  the  bending  moment  of  wire  at  dist.  LI  from  ground. 
MC2  =  the  bending  moment  of  wire  at  dist.  L2  from  ground. 
Mt  =  the  total  bending  moment. 

Then 

FH2  (di+2d2) 
Mp= ^-         Ib.-ft. 


24 


[549] 


Sec.  8  MECHANICAL  CALCULATIONS 

Mt  =Mp+Mci+MC2    Ib.-ft. 
T  Mt  f 

~ 


d3    =  di  —  (di  —  d2)  -^r    inches. 
n. 

_Mt     Ibs. 
K     in2. 


18.1152 
Whendx^l.Sda  ** 

K  dl3 

122.208 

When  di~1.5  d3 

For  values  of  K  for  variations  in  di  and  d3  see  Fig.  322.* 
The  curves  in  Fig.  323 1  were  obtained  as  follows: 

Symbols: 

d0     =  rot  diameter  in  inches, 

di     =  diameter  at  ground  line  in  inches. 

d3    =  diameter  where  load  is  applied  in  inches. 

MO  =  bending  moment  on  rotted  pole  in  Ib.-ft. 

M    =  bending  moment  on  new  pole  in  Ib.-ft. 

s      =  fibre  stress  per  square  inch  at  bending  moment  M. 

s0     =  fibre  stress  per  square  inch  at  bending  moment  Mc 

=  Mp 

_(di-d3)d32s 
18.1152 

M     -  d°3  s° 
"122.208 

_]Vlp_ dp3  SQ 

~H  "122.208  (di— ds)  d32  s 

18.1152 
18.1152  s0 


'122.208s   'Adi 


o 


**  The  weakest  section  of  a  wood  pole  is  where  the  diameter  is  equal  to  1.5 
times  the  diameter  of  the  point  of  application  of  the  resultant  load. 

*  For  sawed  square  timber  K  as  found  from  Fig.  322  should  be  increased  70%. ] 
t  Curves  are  equally  correct  for  sawed  square  timber  or  round  timber. 

[  550  ] 


MECHANICAL  CALCULATIONS 


Sec.  8 


,J7 


2 


// 


Or?* 


*Y 


z 


8      10     12      14     /6      18     20     22     24     2 6     28     30     22 

D/AM£r££  IN  INCHES  AT  THE  POIMT  OF 

SUPPOBT,  (THE  GROUND  LINE]  -of/ 
FIG.  322.    Fibre  stress  in  ;—  per  Ib-ft.  of  bending  moment,=i. 


[551] 


Sec.  8 


MECHANICAL  CALCULATIONS 


too 


70 


20 


.6 


d, 

FIG.  323.  —  Relation  between  rotted  diameter  of  pole,  bending  moment  and  fibre 

stress. 


[  552  ] 


MECHANICAL  CALCULATIONS  Sec.  8 


di 

d0  as  a  percent  of  d] 
3 


The  curves  in  Fig.  323  illustrate  the  percent  of  the  original  diame- 
ter to  which  a  given  pole  may  rot  before  the  strength  is  less  than  that 
of  a  sound  pole;  also  the  percent  of  the  original  diameter  at  which 
the  pole  will  break. 

If  the  bending  moment  remains  constant,  iy  =  l;  the  percentage 
rot  diameter  i.e.,  the  ratio  of  the  diameter  of  the  rotted  pole  to  the 
original  ground  line  diameter  will  vary  in  accordance  with  curve 

(1)  depending  upon  the  ratio  -p.  If  the  stress  is  greater  the  value  of 
the  rotted  diameter  will  be  determined  by  the  curve  indicated  by  the 
value  of  — -,  tj  remaining  equal  to  one. 

So 

If  the  load  on  the  pole  is  increased  TJ  will  be  greater  than  one  and 
the  rotted  diameter  of  the  pole  is  determined  by  the  curve  indicated 

by  the  value  of  TJ  — .    These  curves  may  be  interpolated  with  ac- 

SQ 

curacy. 

Problem: 

Find  the  top  and  ground  line  diameter  necessary  for  a  40  ft.  chest- 
nut pole,  set  6  ft.  in  the  ground  to  which  are  attached  3  No.  00  bare 
stranded  copper  wires,  one  at  the  top  and  two  3  ft.  from  the  top; 
the  wires  coated  with  ^"  of  ice,  and  a  wind  pressure  of  8  Ibs.  per 
square  foot  on  the  pole  and  the  ice  covered  wires.  The  adjacent 
spans  are  150  and  200  feet  long. 

Solution: 

Solve  first  for  wire  and  ice  load  alone.     Table  82  for  No.  00 
stranded  copper,  %  ice  and  8  Ibs.  wind  F0  =  0.947. 
Wire  on  top  of  pole. 

MCI  =  1  X0.947X34  (15Q+2QQ)  =5)65o  lbs.-ft. 
Wires  on  cross  arms. 

MC2=  2X0.947X31  (150+20Q}  =  10,290  lbs.-ft. 

Mci+Mc2  =  15,940  lbs.-ft. 

Since  the  top  and  ground  line  diameter  of  the  pole  are  not  known, 
it  is  necessary  to  assume  a  value  for  the  maximum  allowable  fibre 
stress  which  in  this  solution  is  made  1200  Ibs.  per  square  inch. 

[553] 


Sec.  8  MECHANICAL  CALCULATIONS 

Then 

Mci  +  MC2,  15,940  _ 
=~~ 


From  Fig.  322  for  K  =  13.3.  A  40  ft.  class  "  B  "  pole,  Sec.  2,  Art.  16, 
may  be  used,  since  it  has  a  ground  line  and  top  diameter  equal  to 
about  13"  and  7"  respectively. 

Since,  as  mentioned  in  the  foregoing,  the  wind  pressure  has  been 
considered  for  the  wires  only,  it  is  necessary  in  order  to  find  the  maxi- 
mum fibre  stress  in  the  pole  to  recalculate  the  problem  for  the  pole 
selected  by  the  above  method,  including  in  the  calculation  the 
effective  wind  pressure  on  the  pole. 


8  X  (34)2  X  (13.7  +2X7)     orfin,uff 
Mp  =  --  =2  ---  =3,560  Ib.-ft. 

MCi=   5,650  Ib.-ft. 
MC2  =   10,290  Ibs.-ft. 
Mt  =    19,500  Ib.-ft. 

X  34X8  =  234.5  Ibs. 


=  3321bs. 


L_          19,500          _  19,500 
~234.5+166+332~732^~ 


Fords  =8.46 
di-13.7 

Find  K  =  21  (Fig.  322). 

s  =  M*  =  i^M  =  928  Ibs.  per  square  inch. 
K.  2i\ 

Having  determined  for  the  selected  pole  the  maximum  fibre  stress 
per  square  inch  (928  pounds)  it  follows  that  a  certain  decrease  in 
ground  line  diameter  may  take  place  due  to  rotting  before  the  pole 
will  fail.  This  value  is  determined  as  follows  : 

[554] 


MECHANICAL  CALCULATIONS 


Sec.  8 


\ 


\ 


v 

\ 


*8 

§ 

^ 
* 


^ 

.1 

^ 
^ 
5 
s? 


[  555  ] 


Sec.  8  MECHANICAL  CALCULATIONS 

Assume  the  bending  moment  on  the  pole  to  be  the  same  when 
rotted  as  when  new; 

Mo 

Then  77=^  =  ! 
M 

The  modulus  of  rupture  of  chestnut  is  5100  Ibs.  per  square  inch, 

s  928 

therefore,  to  break  the  pole  —  must  equal  ^^-  =0.182. 

So 

d3       8.46 


Interpolation  of  the  curves  in  Fig.  323  between  ij  —  =  0.1  and  0.2 

So 

shows  that  the  diameter  may  be  rotted  to  56%  of  the  original  ground 
line  diameter. 

56  X 13  7 
Rotted   diameter  = '     =7.66  inches. 

20.  Dead  End  Loading. 
MCI  =   LI  Tut  ru 
MC2=   L2Tu2n2 

Problem: 

Find  the  stress  in  a  40  ft.  chestnut  pole,  set  six  feet  in  the  ground, 
when  subjected  to  the  bending  moment  due  to  dead  ending  three 
No.  00  bare  stranded  copper  wires,  one  at  the  top  and  two,  three 
feet  from  the  top.  Assume  a  200  ft.  span. 

Solution: 

Tui=  Tu2  =  1,975  Ibs.     (From  Art.  13,  Prob.  1.) 

m   =    1 

n2   =   2 

MCi=   34  X  1,975  XI  =67,150  Ib.-ft. 
MC2=   SIX  1,975X2  =  122,300  Ib.-ft. 
Mt  =   67,150  +  122,300  =  189,450. 

Mt     189,450 
K  =  V==T200~- 
No  standard  40-ft.  pole  will  meet  this  condition.     (See  Fig.  322.) 

T,  _Mt_  189,450       ? 
=  ~F==   5,100   = 

This  will  break  a  standard  40-ft.  pole.  Assuming  in  both  cases 
that  the  pole  does  not  bend  and  relieve  the  wire  stress.  Such  a  pole 
may  be  used,  if  guyed  as  shown  in  Art.  22. 

F  556  1 


MECHANICAL  CALCULATIONS  Sec.  8 

21.  Bends  in  Line  or  change  in  line  direction. 

Assume  a  15°  angular  change  in  the  line. 

From  Fig.  324  TUi  equals  26%  of  the  tension  in  wires. 

Tui=   Tu2  =  .26Xl,975=5141bs.     (Art.  13,  Prob.  1.) 
MCi=   34  X  514X1  =  17,480  Ibs.-ft. 
MC2=   3lX514X2  =  31,9001bs.-ft. 
Mt  =   49,380  Ibs.-ft. 

A  15°  bend  is  similar  in  effect  to  dead  ending,  but  not  to  so  great 
an  extent. 

For  a  90°  bend,  however,  from  Fig.  324. 

Tu    =    1.41X1,975  =2,785  Ibs. 
Mci  =   34  X  2,785  X 1  =94,600  Ibs.-ft. 
MC2  =   31  X 2,785  X2  =  172,900  Ibs.-ft. 

Mt  =    267,500  Ibs.-ft. 

which  is  worse  than  dead  end  loading. 


FIG.  325. 


If  it  is  desired  to  use  pull  instead  of  the  curve  in  Fig.  324. 
P     =   pull  (Fig.  325). 
Tu   =   resulting  tension  on  wire  supports. 
T     =   tension  in  wires. 

Then 

_2PT 
lu  ==~~ 


22.  GUYING. 

Mt  =  total  moment  on  pole. 

Lg   =  height  of  point  of  guy  attachment  from  ground. 

L'g  =  distance  of  guy  anchor  from  base  of  pole. 

Tg  =  tension  in  guy  wire. 

[  557  ] 


Sec. 


MECHANICAL  CALCULATIONS 

POLE 


Mt=TtL 

Mt 


FIG.  326. 


Lg  sine  a 

1  (Fig.  326.) 

Sine  a= — r 


POLE 


GuySWi 


L' 


Mt 


•9   ' 
FIG.  327. 


Lg  sine  a 
Sine  a  =  — ,-= 


(Fig.  327.) 


Problem: 

Assuming  the  bending  moment  as  determined  in  Art  21  for  a  90° 
bend. 

Mt  =  267,500  lbs.-ft. 

Guy  attached  three  feet  from  top  of  pole. 

Lg  =  31  feet;  foot  of  guy  30  ft.  from  base  of  pole  (Fig.  326). 

Sine  a  =  — 7==  =  =  0.696 


[558] 


267,500 


MECHANICAL  CALCULATIONS  Sec.  8 

If  a  factor  of  safety  of  three  is  used  the  breaking  strength  of  the 
guy  must  be  12,400X3=37,200  Ibs.  This  necessitates  the  use  of 
two  Siemens  Martin  y%  galvanized  strands  having  an  ultimate 
strength  of  19,000  Ibs.  each. 

19,000X2  =  38,000  Ibs. 

23.  CONCRETE  AND  STEEL  STRUCTURES.  It  will  be  noted 
from  the  above  that  the  solutions  have  been  confined  to  wood  poles 
and  cross-arms  for  the  reason  that  the  design  of  steel  and  concrete 
structures  introduce  engineering  problems  which  cover  such  a  num- 
ber of  variables  that  formulae  for  their  solution  would  require  a 
treatise  on  structural  design. 

These  problems  are  essentially  structural  engineering  problems 
and  their  solution  should  be  made  by  men  familiar  with  such  work. 


BIBLIOGRAPHY. 

N.  E.  L.  A.  Overhead  Line  Committee  Report,  1911. 

U.  S.  Weather  Bureau. 

Transactions  of  International  Electrical  Congress,  1904. 

A.  I.  E.  E.,  June,  1911,  Mr.  P.  H.  Thomas. 

Franklin  &  Esty  Electrical  Engineering. 

Mechanics  of  Materials,  Merriman. 

Overhead  Electric  Power  Transmission,  Still. 


[559] 


SECTION  9 

PRESERVATIVE  TREATMENT  OF  POLES 
AND  CROSS-ARMS 


PART  I 
GENERAL  DATA 


PART  II 
RECOMMENDED  PRACTICE   AND   SPECIFICATIONS 


PART  III 
APPENDICES 


SECTION  9 

PRESERVATIVE  TREATMENT  OF  POLES  AND 
CROSS-ARMS 

PART  I— GENERAL  DATA 


TABLE  OF  CONTENTS 

ARTICLE 

Introductory 1 

Seasoning 

General 2 

Manner  of  Storing  Poles  and  Cross-arms 3 

Spacing 4 

Roofing 5 

Summary  on  Seasoning 6 

Preservatives 

General 7 

Structure  of  Wood 8 

Sap  Wood 9 

Decay  of  Wood 10 

Preservative  Agents 11 

Preservation  with  Oils 12 

Coal  Tar  Creosote 13 

Water  Gas  Tar  Creosote 14 

Petroleum  Oil 15 

Wood  Creosote 16 

Preservation  with  Salts 17 

Summary 18 

Processes 

General 19 

High  Artificial  Pressure  Processes 20 

Full  Cell  Treatment:— Bethell 21 

Burnett .  . 22 

Wellhouse 23 

Rutgers 24 

Card 25 

Allardyce     26 

Empty  Cell  Treatment :— Riiping 27 

Lowry 28 

Atmospheric  Pressure  Processes 29 

[563] 


Sec.  9  WOOD  PRESERVATION 

ARTICLE 

Full  Cell  Treatment,  Steeping  in  Cold  Preservative ....  30 

Hot  or  Boiling 31 

Alternate,  Hot  and  Cold 32 

Empty  Cell  Treatment — open  tank 33 

Low  Artificial  Pressure  Systems,  Full  or  Empty  Cell 34 

Miscellaneous  Treatments,  Brush 35 

Brush  combined  with  open  tank  36 

Jacket  or  Butt  setting 37 


[564J 


1.  INTRODUCTORY.    The  following   chapter   on  preservative 
treatments  consists  of  extracts  from  the  1910  and   1911   reports 
of   this   Association's   Committee   on   Preservative  Treatment  of 
Wood  Poles  and  Cross-arms.     The  first   named  report  has  been 
condensed  in  order  to  present  only  the  sections  on  seasoning,  pre- 
servatives, and  processes.     These  general  descriptions  of  preserva- 
tive  practises  are  given  not  only  because   they  are   historically 
and  scientifically  interesting,   but   also  to  properly   introduce   the 
more   definite    recommendations    and   specifications    presented   in 
Part  II.     Attention  is  called  to  this,  as  the  conclusions  regarding 
the  nature  of  preservatives  and  methods  of  treatment  given  in 
Part  II  were  intended  to  supersede  the  more  general  conclusions 
contained  in  Part  I. 

Much  valuable  data  have  necessarily  been  omitted,  particularly 
the  conclusions  of  the  committee  on  preservative  methods  con- 
cerning which  they  were  unable  to  procure  sufficient  information 
to  justify  recommendation.  The  reports  of  this  committee  are 
undoubtedly  among  the  most  valuable  of  the  association  and  will 
be  found  printed  in  full  in  the  1910  and  1911  proceedings. 

SEASONING 

2.  General.     Whether  or  not  poles  or  cross-arms  are  to  receive 
preservative  treatment,  there  can  be  no  doubt  that  it  invariably 

eiys  to  season  them  properly  before  putting  them  into  service, 
nder  ordinary  conditions,  the  life  of  a  well-seasoned,  untreated 
pole  should  be  at  least  30  per  cent  greater  than  that  of  an  untreated 
green  pole,  and  the  life  of  cross-arms  is  increased  in  about  the  same 
proportion  through  proper  seasoning.  For  general  purposes,  air- 
dried  timber  should  give  the  best  results  in  regard  to  the  strength 
after  seasoning,  decreased  moisture  content  in  the  wood  under  aver- 
age climatic  influences,  and  the  increased  penetrability  afforded  to 
impregnation  by  preservative  fluids. 

Artificial  drying  or  seasoning  methods  such  as  kiln  drying,  oven 
drying  and  steaming  are  employed  for  various  reasons,  but  the  usual 
object  is  to  force  the  drying  process.  It  would  seem  that  where 
poles  and  cross-arms  are  used  in  limited  quantities,  and  the  preserva- 
tive treatment  is  to  be  applied  by  the  pole  consumer,  there  would 
be  no  good  reason  for  resorting  to  artificial  means  of  drymg.  It  is 
true,  however,  that  some  method  of  accelerated  drying  is  imperative 
where  the  wood  is  to  be  treated,  and  sufficient  time  cannot  be  allowed 
to  air-dry  it  thoroughly.  It  is  astonishing  at  this  late  day  to  learn 
that  in  many  instances  poles  and  cross-arms  are  brush-treated  while 
in  a  green  state,  whereby  the  moisture  content  of  the  wood  is  prac- 
tically sealed  within  it,  so  that  in  a  short  time,  when  the  superficial 
coating  is  worn  or  torn  away  fungi  are  admitted  to  the  interior, 
and  accelerated  decay  is  encouraged.  If  poles  and  cross-arms  cannot 
be  sufficiently  air-dried,  or  if  any  form  of  artificial  drying  is  not 
resorted  to,  it  is  best  not  to  attempt  any  such  treatment  before  the 
poles  and  cross-arms  are  installed,  and  if  so  installed,  sufficient  time 

[565] 


Sec.  9 


WOOD  PRESERVATION 


should  be  allowed  to  season  the  arms  before  treating  them.     Never- 
theless, local  conditions  are  apt  to  govern;    as,  for  instance,  poles 
are  often  required  to  be  kept  painted  under  franchise  or  ordinance 
requirements. 
3.  Manner    of    Storing    Poles    and    Cross-arms.    In    general, 


whether  poles  are  stored  at  some  distributing  point  or  are  distributed 
along  construction  routes,  the  first  care  should  be  to  keep  them 
clear  from  the  ground.  If  the  bottom  tier  of  a  pile  of  poles  is 
placed  at  a  sufficient  height  from  the  ground,  say  not  less  than  two 
feet,  two  necessary  things  will  be  accomplished — the  wood  will  is 
farther  removed  from  decay  infection  and,  owing  to  the  freer  cir- 

[  566  ] 


WOOD  PRESERVATION 


Sec.  9 


culation  of  air,  the  seasoning  process  will  be  more  thoroughly  and 
quickly  accomplished.  If  the  poles  are  to  remain  for  any  length  of 
time  in  one  position,  the  tiers  should  be  separated,  and,  if  possible, 
the  poles  should  not  come  in  contact.  (Figs.  328  and  329.) 

Forest  Circular  No.  151  gives  some  valuable  suggestions  covering 
the  proper  piling  and  storage  of  cross-arms: 


l! 

3-2 


_M  ifS    3 

V  W)  a 

|-cg 


a.- 


''In  addition  to  natural  factors,  another  of  hardly  less  importance 
is  introduced  in  the  manner  of  piling  the  timber.  In  general  com- 
mercial practice,  economy  of  space  and  handling  are  rightly  con- 
sidered of  the  first  importance,  and  all  other  considerations  are  made 

[567] 


Sec.  9 


WOOD  PRESERVATION 


subservient.  Present  practice  does  not  secure  the  best  results,  but 
if  there  were  no  means  by  which  these  could  be  attained,  without 
the  sacrifice  of  labor  and  of  space  economy,  no  change  in  the  present 
pile  forms  would  be  recommended.  However,  the  adoption  of 
proper  methods  does  not  appreciably  increase  either  labor  or  space. 


4.  Spacing.  "In  most  seasoning  yards,  the  arms  are  piled  closely 
together,  there  being  about  28  on  each  tier.  (Fig.  330.)  In  some 
cases,  however,  a  partial  improvement  is  made  by  changing  the 
position  of  either  one  arm  or  two  arms  at  the  centre  and  ends  of  the 
tiers,  as  is  shown  in  Fig.  331.  Both  of  these  pile-forms  retard  the 
evaporation  of  the  moisture  from  the  wood.  In  the  closest  pile  the 

[568] 


WOOD  PRESERVATION 


Sec.  9 


circulation  of  air  is  almost  entirely  shut  off,  and  all  evaporation 
must  take  place  from  the  ends  of  the  timbers.  In  case  of  heavy  rain 
or  melting  snow  the  water  trickles  down  over  the  timber,  and  the 
dampness  thus  promoted,  together  with  even  moderate  temperatures, 
stimulates  the  growth  of  fungi,  while  the  close  contact  of  the  timbers 
permits  a  rapid  spread  of  infection. 


"It  often  happens,  therefore,  that  where  timber  is  so  piled  the 
growth  of  wood-destroying  fungi  has  reached  a  serious  stage  before 
the  timber  itself  has  attained  its  air-dry  condition.  Hence  it  is  not 
uncommon  to  hear  the  assertion  that  the  sap-wood  of  loblolly  pine 
will  rot  before  it  can  become  air-dry.  Such  an  assertion  is  probably 

[  569  ] 


Sec.  9 


WOOD  PRESERVATION 


untrue  in  every  case,  and  it  is  certain  that  loblolly,  or  any  other 
timber,  in  a  form  so  well  adapted  for  rapid  evaporation  of  moisture 
as  cross-arms,  can  be  fully  seasoned  in  any  part  of  the  country  without 
a  risk  of  deterioration  during  the  seasoning  period.  By  adopting 
the  pile  form  shown  in  Fig.  331,  a  circulation  of  air  is  permitted  along 


the  sides  of  the  arms.  The  upper  and  lower  faces  are  still  so  closely 
crowded  together  than  no  air  current  can  pass  between  them. 
Obviously,  the  next  step  is  to  separate  the  arms  from  each  other  by 
a  space  of  sufficient  size  to  insure  a  thorough  circulation  of  the  air 
on  all  sides  of  the  arms,  and  yet  not  so  large  as  to  consume  unneces- 

I  570] 


WOOD  PRESERVATION 


Sec.  9 


sary  space.    When  these  two  requirements  are  met,  the  ideal  form 
of  pile  is  attained. 

"Many  experiments  have  shown  that  if  from  20  to  22  arms  are 
allowed  to  each  tier,  and  arranged  as  shown  in  Fig.  332,  most  of  the 
desired  results  will  be  attained.-  This  pile,  called  for  convenience 
the  20-by-20  form,  compared  with  those  in  general  use,  gives  a  sur- 


prising difference  in  the  rate  of  seasoning.  For  example,  sap-arms 
of  the  July  allotment  were  piled  as  in  Figs.  331  and  332.  Those  in  the 
20-by-20  pile  dried  out  to  a  weight  of  34.1  pounds  per  arm  in  a  little 
more  than  six  weeks,  while  more  than  sixteen  weeks  elapsed  before 
a  like  weight  was  reached  by  the  arms  in  the  figure,  or  28-by-28  pile. 

[571] 


Sec.  9 


WOOD  PRESERVATION 


The  only  difference  in  the  two  piles  was  in  the  number  of  arms  to 
the  tier.  Had  the  arms  in  the  28-by-28  pile  been  packed  closely 
together,  as  in  Fig.  330,  the  difference  in  the  rate  of  seasoning  would 
have  been  much  greater. 

5.  Roofing.     "  Under  climatic  conditions,  such  as  prevail  in  most 

r :   • — — — i 


parts  of  the  United  States  throughout  the  greater  portion  of  the 
year,  it  is  best  to  expose  the  timber  directly  to  the  sun  and  rain. 
During  the  Winter  months,  however,  or  whenever  there  is  a  preva- 
lence of  rain  or  snow,  excellent  results  will  be  secured  by  piling  the 
arms  under  a  roof,  without  walls,  or  by  constructing  a  rude  roof  over 

[572] 


WOOD  PRESERVATION 


Sec   9 


each  pile.  This  latter  method  will  probably  be  the  cheapest,  as  it 
avoids  the  difficulty  of  handling  the  arms  in  a  confined  space.  If 
the  boards  are  placed  as  shown  in  Fig.  333,  the  arms  below  will  remain 
dry  during  even  a  heavy  rain  or  snow-storm.  Of  the  two,  snow  is 
the  more  serious,  since  it  generally  takes  longer  to  evaporate;  and 


during  its  slow  melting  the  partially  seasoned  timber  will  absorb 
moisture  without  giving  it  off.  In  all  cases,  the  roofing  should 
extend  out  over  the  pile  on  all  sides  to  protect  the  ends  of  the  arms, 
for  it  is  there  that  the  evaporation  or  absorption  of  moisture  is  most 
rapid. 

"It  is  not  advisable  to  attempt  to  form  the  roof  with  the  arms 

[  573  ] 


Sec.  9 


WOOD  PRESERVATION 


themselves, -as  shown  in  Fig.  334,  for  three  reasons:  In  the  first  place, 
the  roof  is  too  short  and  too  narrow  to  give  proper  protection  to  the 
ends  and  sides  of  the  pile;  in  the  second  place,  the  exposure  of  the 
roof  arms  to  maximum  changes  of  atmospheric  condition  causes 
severe  checking  and  warping,  with  a  consequent  loss  of  timber; 
and,  in  the  third  place,  considerably  more  labor  is  required  to  handle 
the  greater  number  of  pieces  necessary  in  constructing  the  roof." 
Also  see  Fig.  335  for  still  another  method  of  cross-arm  racking. 

The  length  of  time  necessary  to  effect  sufficient  seasoning  of 
either  poles  or  cross-arms  decides  whether  the  timber  should  be  cut 
in  the  Winter  or  Spring.  Wood  that  will  season  to  the  proper  stage 
in  approximately  six  months  can  safely  be  cut  in  the  Spring,  while 
that  requiring  a  longer  period  should  be  cut  in  the  Winter  so  as  not 
to  carry  the  seasoning  stock  over  the  late  Fall  and  Winter.  This 
is  obvious,  as  timber  cut  in  the  Spring  will  receive  the  effect  of  the 
hot  Summer  sun,  while  the  Autumn-cut  timber  must  be  held  during 
the  Winter  months  when  the  seasoning  process  is  at  its  slowest  stage. 
The  United  States  Forest  Service  states  that  no  poles  should  be  cut 
in  Summer  or  early  Autumn,  as  the  stumps  of  poles  cut  at  that  time 
will  not  give  forth  vigorous  sprouts.  Some  experiments  conducted 
recently  in  California  by  the  Government  show  the  following  results 
in  regard  to  seasonal  cutting  of  western  yellow  pine  and  western  red 
cedar  (Tables  87  and  88). 


TABLE  87 

SEASONING  OF  WESTERN  YELLOW  PINE  POLES, 
MADERA  COUNTY,  CALIFORNIA 

Month 

AUTUMN 
CUT 

WINTER 
CUT 

SPRING  CUT 

SUMMER 
CUT 

Weight 

Cubic 
Foot 
Pounds 

Per 

Cent  of 
Green 
Weight 
Lost 

Weight 
per 
Cubic 
Foot 
Pounds 

Per 

Cent  of 
Green 
Weight 
Lost 

Weight 
per 
Cubic 
Foot 
Pounds 

Per 
Cent  of 
Green 
Weight 
Lost 

Weight 
per 
Cubic 
Foot 
Pounds 

Per 

Cent  of 
Green 
Weight 
Lost 

October  
November  . 
December   . 
January.  .    . 
February.    . 
March  ...    . 
April  
May  
June  
July  
August  
September  . 
October..  .. 

64.1 
54.0 
51.3 
52.6 
54.1 
50.4 
46.0 
41.7 
37.6 
33.7 
30.3 

15^8 
20.0 
17.9 
15.6 
21.4 
28.2 
35.0 
41.4 
47.5 
52.7 

IM 

62.6 
56.2 
47.7 
40.4 
36.0 
32.8 

eio 

15.6 
28.4 
39.3 
45.9 
50.8 

65.2 
51.5 
44.4 
39.8 
36.2 
32.6 

2i!o 

31.9 
39.0 

44.5 
50.0 

MJ 

40.3 
33.8 
31.8 

37i8 
47.8 
51.0 

Average  pole  "(40  feet)  contained  26.1  cubic  feet. 
[574] 


WOOD  PRESERVATION 


Sec.  9 


TABLE  88 
SEASONING  OF  WESTERN  RED  CEDAR  POLES, 
LOS  ANGELES,  CALIFORNIA 
Weight  per  Cubic  Foot  Each  Month  from  Time  of  Cutting.* 

Month 

Summer  Cut 

Fall  Cut 

Winter  Cut 

Spring  Cut 

Juiy  

42.4f 

42Uf 

ssioj 

29.0 
26.5 
25.5 

42.4t 

S6.12J 
28.25 
26.30 
25.3 

42.4t 

S8.12t 
33.0 
31.0 
29.3 
28.0 

August           

October      

November  

December  

32.5J 
31.1 
30.0 
28.5 
26.5 
25.0 
23.5 
23.46 

February  

March 

April  

May 

June  

July 

August  

September 

October  
November  

*  The  average  volume  of  300  poles  (40  feet  8  inches)  was  27.34  cubic  feet. 
tAbsplute  green  weight. 

j  Weight  on  arrival  at  Los  Angeles,  California,  from  three  to  seven  months 
ifter  cutting. 


TABLE  89 
RATE  OF  SEASONING  OF   CHESTNUT  POLES  CUT  AT 
DIFFERENT  TIMES  OF  THE  YEAR 

FALL  CUT 

WINTER  CUT 

SPRING  CUT 

SUMMER  CUT 

Time 
Sea- 
soned 
Days 

Mois- 
ture 
Con- 
tent 
Per 
Cent 

Weight 
Per 
Cubic 
Foot 
Pounds 

Mois- 
ture 
Con- 
tent 
Per 
Cent 

Weight 
Per 
Cubic 
Foot 
Pounds 

Mois- 
ture 
Con- 
tent 
Per 
Cent 

Weight 
Per 
Cubic 
Foot 
Pounds 

Mois- 
ture 
Con- 
tent 
Per 
Cent 

Weight 
Per 
Cubic 
Foot 
Pounds 

0 
30 
60 
90 
120 
150 
180 
210 
240 
270 
300 
330 
360 

85.4 
72.0 
68.4 
66.9 
65.8 
64.3 
62.2 
59.2 
56.0 
53.0 
50.8 
49.1 
47.8 

56.4 
52.3 
51.2 
50.7 
50.1 
49.9 
49.3 
48.4 
47.4 
46.5 
45.8 
45.3 
44.9 

85.6 
77.4 
72.6 
68.7 
64.8 
60.6 
56.8 
53.7 
51.2 
49.3 

56.4 
53.9 
52.5 
51.3 
50.1 
48.8 
47.7 
46.7 
46.0 
45.4 

83.0 
70.5 
64.3 
60.0 
56.5 
53.7 
51.7 

5.6 
51.8 
49.9 
48.6 
47.6 
46.7 
46.1 

84.4 
67.9 
60.6 
57.5 
55.9 

56.1 
51.0 
48.8 
47.9 
47.4 

[575] 


Sec.  9 


WOOD  PRESERVATION 


The  preceding  table  taken  from  Forest  Circular  No.  147  shows 
the  rate  of  seasoning  of  Maryland  chestnut  poles  cut  at  different 
times  of  the  year  (Table  89). 

To  cover  more  fully  general  geographical  conditions,  the  follow- 
ing, taken  from  United  States  Forest  Service  Circular  No.  136  shows 
the  rate  of  seasoning  of  Michigan  arborvitae  poles  by  seasonal  cuts: 


TABLE  90 

WEIGHT  AND  MOISTURE  CONTENT  BY  SEASONAL  CUTS 

SPRING  CUT 

SUMMER  CUT 

AUTUMN  CUT 

WINTER  CUT 

Mois- 

Mois- 

Mois- 

Mois- 

ture 

ture 

ture 

ture 

Time 
Sea- 

Con- 
tent 

Weight 

Con- 
tent 

Weight 

Con- 
tent 

Weight 

Con- 
tent 

Weight 

soned 
Days 

in  Re- 
lation 
to  Dry 
Weight 

Cubic 
Foot 
Pounds 

in  Re- 
lation 
to  Dry 
Weight 

per 
Cubic 
Foot 
Pounds 

in  Re- 
lation 
to  Dry 
Weight 

Cubic 
Foot 
Pounds 

in  Re- 
lation 
to  Dry 
Weight 

per 
Cubic 
Foot 
Pounds 

Per 

Per 

Per 

Per 

Cent 

Cent 

Cent 

Cent 

0 

77.4 

31.9 

81.7 

32.7 

79.0 

32.2 

90.0 

34.2 

30 

53.8 

27.7 

61.4 

29.1 

79.0 

32.2 

90.0 

34.2 

60 

49.7 

26.9 

51.9 

27.3 

79.0 

32.2 

90.0 

34.2 

90 

48.4 

26. 

49.1 

26. 

79.0 

32.2 

86.4 

33.6 

120 

48.3 

26. 

49.0 

26. 

79.0 

32.2 

53.0 

27.5 

150 

48.3 

26. 

49.0 

26. 

77.2 

31.9 

42.3 

25.6 

180 

48.3 

26. 

49.0 

26. 

43.0 

25.7 

37.5 

24.8 

210 

48.3 

26. 

49.0 

26. 

33.2 

24.0 

34.3 

24.2 

240 

48.3 

26.7 

48.0 

26.6 

29.0 

23.2 

270 

48.3 

26.7 

40.5 

25.3 

27.2 

22.9 

300 

48.3 

26.7 

35.7 

24.4 

330 

44.2 

26.0 

32.9 

23.9 

360 

36.0 

24.5 

30.7 

23.5 

390 

33.7 

24.1 

420 

32.3 

23.8 

The  following  tables  were  taken  from  Forest  Service  Circular 
No.  151.  They  show  the  green  weight  according  to  the  season 
when  cut  and  the  comparative  rates  of  seasoning  of  North  Carolina 
loblolly  pine,  heart-wood,  sap-wood  and  intermediate  grade  cross- 
arms  (Tables  91  and  92) : 


TABJLE  91 

COMPARATIVE  WEIGHTS  OF  GREEN  NORTH  CAROLINA 
LOBLOLLY  PINE 

WEIGHT  PER  CUBIC  FOOT 

Portion  of  Tree 

Autumn 
Pounds 

Spring 
Pounds 

Summer 
Pounds 

Winter 
Pounds 

42.4 
48.8 
55.6 

42.6 
49.9 
57.4 

45.1 
50.2 
57.4 

45.5 
51.1 
58.2 

Intermediate  
Sap-wood  

t  576  ] 


WOOD  PRESERVATION 


Sec.  9 


TABLE  92 

COMPARATIVE  RATES  OF  SEASONING  OF  LOBLOLLY 

PINE  HEART-WOOD,  SAPWOOD  AND  INTERMEDIATE 
CROSSARMS 

Days 
Sea- 
soned 

HEART-WOOD 

SAP-WOOD 

INTERMEDIATE 

Weight 
Per 
Arm 
Pounds 

Weight 
Per 
Cubic 
Foot 
Pounds 

Mois- 
ture 
Con- 
tent 
Per 
Cent 

Weight 
Per 
Arm 
Pounds 

Weight 
Per 
Cubic 
Foot 
Pounds 

Mois- 
ture 
Con- 
tent 
Per 
Cent 

Weight 
Per 
Arm 
Pounds 

Weight 
Per 
Cubic 
Foot 
Pounds 

Mois- 
ture 
Con- 
tent 
"Per 
Cent 

0 
30 
60 
90 
120 
150 
180 

38.8 
34.2 
33.9 
34.3 
34.2 
33.9 
33.6 

42.6 
37.6 
37.3 
37.3 
37.6 
37.3 
36.9 

51.5 
33.4 
32.5 
33.8 
33.7 
32.3 
31.2 

52.7 
34.5 
32.6 
32.6 
32.5 
32.1 
31.6 

57.9 
37.9 
35.8 
35.8 
35.7 
35.3 
34.7 

105.8 
34.8 
27.2 
27.3 
26.9 
25.4 
23.6 

45.8 
34.3 
33.3 
33.4 
33.4 
33.0 
32.5 

50.3 
37.7 
36.6 
36.7 
36.7 
36.3 
35.7 

79.0 
34.0 
30.0 
30.3 
30.3 
29.0 
26.9 

The  foregoing  Government  tests  conducted  in  California  on 
western  yellow  pine  and  western  red  cedar  would  indicate  that  the 
yellow  pine  should  be  air-dry  and  ready  for  preservative  treatment 
when  it  had  lost  50  per  cent  of  its  original  weight,  and  that  the  red 
cedar  should  lose  40  per  cent  of  its  original  weight  before  treating. 
Chestnut  poles  should  be  ready  to  set  or  to  receive  brush  treatment 
when  they  have  lost  about  15  per  cent  of  their  original  weight. 
According  to  Forest  Service  Circular  No.  136,  the  air-dry  weight  of 
arborvitae  should  be  about  73  per  cent  of  the  green  weight,  or  a  loss 
of  27  per  cent  of  its  original  weight. 

The  above  data  are  given  to  illustrate  the  seasoning  character- 
istics of  some  of  the  more  representative  types  of  wood.  The 
Government  tests  cited  were  selected  because  of  their  undoubted 
accuracy. 

6.  Summary  on  Seasoning.*  1.  Poles  should  be  cut  from  sound 
standing  timber.  , 

2.  The  bark  should  be  well  peeled  from  poles  which  are  to  be 
seasoned,  and  particularly  from  those  that  are  to  be  treated,  as  the 
inner  bark  offers  much  resistance  to  the  impregnating  fluid,  and  in 
time  this  bark  peels,  leaving  the  untreated  wood  exposed  to  the  attack 
of  fungi. 

3.  Care  should  be  taken  in  the  handling  and  felling  of  trees,  as 
those  which  are  split  in  felling,  or  are  otherwise  roughly  handled, 
may  afterwards  experience  serious  checking. 

*  For  further  data,  see  Bulletin  No.  84  of  the  Forestry  Service. 
19  [  577  ] 


Sec.  9 


WOOD  PRESERVATION 


4.  Poles  and  crossarms  should  be  properly  piled  and  stored,  and 
as  soon  after  cutting  as  possible. 

5.  The  amount  of  shrinkage  during  seasoning  is  negligible. 

6.  Poles  cut  in  the  Winter  or  Spring  have  before  them  the  best 
period  for  seasoning,  but  late  Fall  and  Winter  offer  the  best  con- 
ditions for  cutting. 

7.  Attention  should  be  paid  to  the  value  of  having  wood  seasoned 
where  cut,  as  a  material  freight-saving  may  often  be  made  in  this  way. 


FIG.  336. — Portion  of  stem  of  four-j  ear-old  pine,  Pinus  Sylvestris,  cut  in  winter, 
(q) ,  transverse  view ;  (1) ,  radial  view ;  (t) ,  tangential  view ;  (f ) ,  early  wood ;  (s) ,  late 
wood ;  (m) ,  medulla;  (p) ,  protoxylem ;  (1,  2, 3, 4) ,  the  four  successive  annular  rings 
of  the  wood;  (i) ,  junction  of  the  wood  of  successive  years;  (me,  ma',  ms'") ,  medul- 
lary rays  in  transverse,  radial,  and  tangential  views;  (ms")  radial  view  of  medullary 
rays  in  the  bast ;  (c) ,  cambium  ting ;  (b) ,  bast ;  (h) ,  resin  canals ;  (br) ,  bark. 

PRESERVATIVES 

7.  General.    In  order  to  understand  the  physical  and  chemical 
action  of  preservatives  in  preventing  or  retarding  decay,  it  will  be 
necessary  to  consider  somewhat  the  structure  of  wood,  the  nature  of 
the  phenomena  which  take  place  when  decay  sets  in,  and  the  causes 
underlying  the  coincident  physical  and  chemical  changes  in  the  wood 
structure  resulting  finally  in  its  more  or  less  complete  destruction. 

8.  Structure  of  Wood.     From  a  chemical  standpoint,  the  pre- 
dominating material  which  enters  into  the  composition  of  wood  is 

[  578  ] 


WOOD  PRESERVATION 


Sec.  9 


cellulose.  The  other  non-cellulose  materials  present  are  known  as 
the  lignone  complex.  The  latter  includes  resins,  gums,  coniferine, 
tannin,  etc.  Physically,  wood  is  made  up  of  small  organs  resembling 
honeycombs  in  appearance,  but  much  smaller.  (Fig.  339.)  These 
organs  are  known  as  wood-cells.  They  are  surrounded  by  distinct 
stiff  walls  and  are  thus  sharply  separated  from  one  another.  The 


FIG.  337. — Tangential  section  of  the  late  wood  of  pine,  (t),  Bordered  pit; 
(tm),  tracheidal  medullary  ray  cells;  (sm),  medullary  ray  cells  containing  starch; 
(et) ,  bordered  pit  only  on  one  side ;  (i) ,  intercellular  space  in  the  medullary  ray. 


canals  from  adjoining  cells  constantly  meet  and  are  sometimes 
widened  at  their  base  into  bordered  pits  (Fig.  337).  The  most  im- 
portant constituent  of  these  cell-walls  is  cellulose.  It  is  present  in 
the  cell-walls  of  most  plants,  except  the  fungi.  The  cell-wall  is  a 
product  of  protoplasm,  and  it  never  consists  of  cellulose  alone,  but 
contains  a  considerable  amount  of  other  substances  which  are  not 
of  a  cellulose  character. 

Lignification  (stiffening  of  the  cell-walls)  is  brought  about  by  the 
deposition  of  coneferine,  vanillin,  and  other  materials  in  the  cell- 
wall.  After  lignification,  cell-walls  are  permeable  to  water  and 
gases.  However,  if  cutin  is  subsequently  deposited  in  the  cell-walls, 

[579] 


Sec.  9 


WOOD  PRESERVATION 


which  have  already  been  lignified,  they  are  rendered  impervious  to 
gases  and  to  water.  While  the  cells  of  woods  vary  to  some  extent, 
those  which  are  provided  with  bordered  pits  and  are  not  sharpened 
at  the  ends  are  spoken  of  as  tracheids  (Fig.  338).  These  contain 
water,  acting  as  water-carriers  for  the  tree.  When  they  become 
inactive  they  are  full  of  air.  It  must  be  remembered  that  these 
tracheids  are  extremely  small.  Tissues  result  from  an  intimate 
union  of  an  aggregation  of  cells.  These  cells  may  fit  closely  to- 


FIG.  338. — (t),  Tracheid  having  large  bordered  pits  which  act  as  water 
carrier;  (gt),  vascular  tracheids  with  similar  functions,  but  with  the  structure 
and  thickenings  of  vessels;  (ft),  fibre  tracheids  with  small  luinina  and  pointed 
ends,  having  only  small,  obliquely  elongated  bordered  pits,  and,  in  extreme 
cases,  exercising  merely  mechanical  functions;  (g),  tracheae,  formed  by  cell  fusion, 
and  provided  with  all  the  different  forms  of  thickenings  by  which  they  are  dis- 
tinguished as  annular,  spiral,  reticulate,  or  pitted  vessels.  All  vessels  function  as 
water  carriers.  If  they  have  small  lumina  and  resemble  tracheids  they  may 
be  distinguished  as  tracheidal  vessels. 

gether,  thus  leaving  no  openings  or  intercellular  spaces  between 
them.  In  case  the  cells  are  not  so  closely  fitted  together,  inter- 
cellular spaces  result  (Fig.  337). 

By  reason  of  variations  in  climatic  conditions,  the  woody  tissue 

*Figs.  336,  337  and  338  reproduced  from  "A  Textbook  of  Botany,"  by  Stras- 
burger  and  others. 

fFigs.  339,  340  and  341  taken  from  Bulletin  No.  1  of  the  Division  of  Forestry. 

[580] 


WOOD  PRESERVATION 


Sec.  9 


exhibits  variation  in  size  and  extent  of  growth,  and  it  is  in  conse- 
quence of  such  variations  that  annular  rings  result  (Fig.  336)  .  During 
the  Spring,  when  energetic  growth  takes  place,  larger  trachial  ele- 


.  339. — Pinus  Palustris,  Miller;  Long-leaved  Pine  Transverse  Section. 
[581] 


Sec.  9 


WOOD  PRESERVATION 


ments  are  developed  than  during  the  Fall  and  Winter  season.  A 
difference  is  therefore  noticed  between  Spring  wood,  which  is  made 
up  of  very  large  tracheids,  and  Autumn  wood,  which  consists  of 
narrow  ones.  It  must  be  remembered  that  the  tissue,  which  is 

"  condition,  composed 
content. 

9.  Sap-wood  is  composed  of  cells  which  go  to  make  the  more 
recent  annular  rings.  These  cells  are  living  organisms  and  act  as 
water-carriers  of  the  tree  (Fig.  338).  Before  these  living  cells  die 
and  enter  into  the  formation  of  dead  tissues  they  produce  certain 


IiariOW    UllcH.       J.U    IHUBU    uc    iciiicniucicu.    oiiau 

made  up  of  tracheids,  is,  in  its  fully  developed 
of  dead-cell  cavities  devoid  of  any  living  conte] 


suostances,  such  as  gums  and  tannins,  which  penetrate  the  cell-walls 
and  also  close,  or  partly  close,  the  cavities.  These  tannins  are  said 
to  prevent  the  decay  of  the  wood,  while  the  gums  are  supposed  to 
close  the  cells  and  thus  end  their  f unction  _as  water-carriers.  These 
tissues,  composed  of  dead  cells  which  are  impermeable  to  water,  go 
to  make  up  heart-wood.  It  will  be  readily  seen  why  heart-wood  is 
so  resistant  to  decay  and  why  it  is  almost  impossible  to  penetrate  it 
by  means  of  impregnating  materials.  Heart-wood  can  usually  be 
distinguished  from  sap-wood  by  its  darker  color,  indicative  of  the 
presence  of  gums  or  tannins.  In  some  trees,  notably  the  willow, 

[  582  ] 


WOOD  PRESERVATION 


Sec.  9 


these  protective  materials  are  absent,  and  the  heart  of  willow  trees  is, 
in  consequence,  usually  decayed,  finally  becoming  hollow. 

10.  Decay  is  the  change  which  takes  place  under  the  influence  of 
certain  agents,  resulting  in  the  decomposition  or  breaking-down  of 
complex  into  simpler  bodies.  The  decay  of  wood  is  generally  due 
to  the  activities  of  certain  low  forms  of  plant  life  known  as  fungi. 
Bacteria  are  also  known  to  cause  decay,  but  their  action  is  little 
understood,  and  in  order  to  illustrate  the  manner  in  which  these 
organisms  promote  decay  a  description  of  the  fungi  will  suffice. 

These  plants  have  their  origin  in  minute  spores  borne  from  place 


1 1  I  0  I 

M        . 


1 

hi 


li 


M 


LUIIi 


FIG.  341. 

to  place  by  the  wind.  Those  that  lodge  and  find  a  suitable  situation 
for  growth,  which  may  be  on  living  or  dead  timber,  germinate, 
provided  the  conditions  are  favorable,  and  at  once  attack  the  wood, 
drawing  their  sustenance  partly  from  the  atmosphere  and  partly 
from  the  contents  of  the  wood-cells;  and  they  finally  attack  the 
cell-walls,  resulting  in  the  breaking  up  of  the  complex  chemical 
substances  and  the  liberation  of  various  gases;  the  result  being  the 
reduction  of  the  wood  into  a  mass  having  little  or  no  resemblance 
to  the  original  material. 

[  583  ] 


Sec.  9 


WOOD  PRESERVATION 


FIG.  342. — Tracheid  of  Pinus  sylvestris,  decomposed  by  Trametes  Pini.  The 
prkaary  cell-wall  has  been  completely  dissolved  as  far  as  a  a.  In  the  lower  part 
the  secondary  and  tertiary  layers  consist  only  of  the  cellulose,  in  which  lime- 
granules  are  distinctly  visible,  b;  filamentous  mycelia,  c,  penetrate  the  walls 
and  make  holes  as  at  d  and  e. 

[584] 


WOOD  PRESERVATION  Sec.  9 

The  action  of  the  various  forms  of  fungi  is  quite  similar.  They 
grow  with  great  rapidity,  sending  out  numerous  threads  which 
penetrate  into  the  wood  and  attack  the  contents  of  the  cells — the 
sugars,  starches  and  oils — and  finally  the  cell-walls.  These  thread- 
like bodies  are  called  hyphae,  and  aggregations  of  them  form  the 
mycelium.  In  Fig.  341  will  be  seen  the  filamentous  mycelia  of  the 
Trametes  Pini.  The  gradual  decomposition  of  wood  by  these  fungi 
is  shown  in  Fig.  342.  When  sufficient  food  has  been  absorbed,  the 
hyphae  form  a  fruiting  body  (Fig.  343  and  Fig.  344)  which  bears  a 
crop  of  spores,  which  in  turn  again  produce  the  mycelium  of  decay. 
Familiar  instances  of  these  fruiting  bodies  are  the  punks  and  toad- 
stools seen  on  decaying  wood.  The  most  favorable  conditions  for 
the  growth  of  fungi  and  other  organisms  of  decay  are  an  abundant 
food  supply,  heat,  moisture,  and  air,  the  amount  of  each  required 
being  dependent  upon  the  kind  of  organism.  A  certain  amount  of 
moisture  must  be  present  or  decay  cannot  set  in.  Air  is  also  es- 
sential, and  thus  may  be  explained  the  lasting  qualities  of  wood 
when  kept  perfectly  dry,  and  the  perfect  state  of  preservation  of 
wood  which  has  been  under  water  for  long  periods;  moisture  being 
lacking  in  the  first  case  and  air  in  the  second.  Again,  if  the  wood  is 
rendered  unfit  for  use  by  an  antiseptic*  or  is  protected  by  a  ger- 
micide, it  will  not  decay.  A  familiar  example,  serving  well  to 
illustrate  the  foregoing,  is  the  rotting  of  fence-posts  and  telephone, 
telegraph,  and  other  poles  in  the  zone  extending  from  just  below 
to  just  above  the  ground  line.  At  the  base  of  the  pole,  while  moisture 
id  present,  air  is  excluded,  while  above  the  ground  the  pole  is  generally 
dry.  It  is  where  moisture  and  air  are  both  present,  the  former 
being  drawn  by  capillary  attraction  from  the  ground,  that  decay 
begins. 

Before  considering  the  action  of  preservatives,  it  may  be  well  to 
emphasize  these  axioms: 

Decay  is  induced  by  the  action  of  living  organisms. 

Moisture,  air,  food,  and  a  certain  amount  of  heat  are  absolutely 
necessary  for  the  growth  of  these  organisms. 

Perfectly  dry  wood  will  not  decay. 

Wood  kept  under  water  will  not  decay. 

Wood  saturated  with  a  substance  which  will  act  as  a  germicide 
will  not  decay. 

Wood  saturated  with  a  substance  which  will  act  as  an  antiseptic 
will  not  decay. 

11.  PRESERVATIVE  AGENTS.  A  theoretical  consideration  of 
the  conditions  under  which  decay  may  start  suggests  the  remedy  in 
the  introduction  into  the  wood  of  some  substance  which  will  act  as  an 
antiseptic  or  a  germicide,  or  prevent  the  entrance  of  moisture  or  air. 
Materials  that  have  been  found  to  possess  one  or  more  of  these 
desirable  qualities  may  be  classified  under  two  general  headings — 

*An  antiseptic  here  is  understood  to  be  any  substance  which  will  inhibit  the 
growth  of  fungi,  while  germicides  are  understood  to  be  substances  which  are 
active  poisons  to  these  growths. 

[  585  ] 


Sec.  9  WOOD  PRESERVATION 

oils  and  salts.  The  most  important  of  the  oils  are  coal-tar  creosote 
or  dead  oil  of  coal-tar,  coal-tar  anthracene  oil,  water-gas  tar  dead 
oil,  and  other  heavy  fractions  therefrom,  petroleum  and  petroleum 
residues,  and  wood  creosote.  Of  the  salts,  zinc  chloride,  mercuric 
chloride,  and  copper  sulphate  are  the  most  extensively  used. 

It  is  generally  believed  that  all  of  these  substances  are  capable  of 
insuring  one  or  more  of  the  conditions  necessary  to  prevent  decay, 
provided,  always,  that  the  wood  remains  saturated  with  the  pre- 
servative. The  chief  difficulty  is  encountered  when  it  is  required 
to  decide  upon  the  extent  of  treatment  necessary  to  insure  the 
desired  length  of  life,  it  being  obviously  inadvisable  to  preserve  the 
timber  beyond  its  mechanical  life.  This  consideration,  however, 
is  much  more  important  in  treating  railroad  ties  than  in  treating 
poles  and  cross-arms,  for  the  reason  that  the  latter  are  subject  to 
little  mechanical  wear.  Another  important  consideration  is  the 
kind  of  preservative  best  suited  for  a  particular  situation.  Climatic 
and  soil  conditions,  in  some  situations,  make  it  inadvisable  to  use  a 
preservative  which,  in  another  situation,  would  prove  perfectly 
satisfactory.  For  example,  in  certain  sections  of  the  country  where 
there  is  a  great  amount  of  rainfall,  zinc  chloride  treatments  are  likely 
to  prove  inefficient  on  account  of  the  lacing  out  of  the  soluble  zinc 
chloride.  On  the  other  hand,  there  are  many  situations  where  it 
could  be  used  to  advantage  both  in  respect  to  cheapness  and  efficiency. 

These  are  important  economic  considerations,  and  the  various 
processes  which  have  been  evolved,  some  employing  antiseptics, 
others  germicides,  and  still  others  offering  only  mechanical  protec- 
tion against  the  entrance  of  moisture  or  air  or  both,  result  from  the 
desire  to  obtain  the  maximum  protection  with  a  minimum  expendi- 
ture of  time  and  money. 

It  may  be  well  here  to  state  that,  as  a  rule,  the  more  of  the  pre- 
servative injected  per  cubic  foot  the  greater  the  life  of  the  timber  is 
likely  to  be.  It  may  be,  and  probably  is  true,  in  a  great  many 
instances,  that  the  employment  of  a  small  amount  of  preservative, 
whether  by  shallow  penetration,  as  in  the  open  tank  and  brush 
treatments,  or  by  the  withdrawal  of  a  portion  of  it  after  it  is  placed 
in  the  wood,  as  in  the  empty  cell  processes,  or  by  its  loss  by  evapora- 
tion or  solution,  will  furnish  a  sufficient  amount  of  protection. 
However,  where  long  protection  is  of  paramount  importance,  deep 
full-cell  penetrations  are  undoubtedly  the  best. 

12.  Preservation  with  Oils.  Whatever  difference  of  opinion  may 
exist  in  the  minds  of  those  interested  in  the  subject  as  to  the  relative 
merits  of  other  preservatives,  one  and  all  agree  that  coal-tar  creosote 
oil,  when  properly  applied,  will  protect  timber  against  decay  for  an 
indefinite  period,  usually  far  in  excess  of  its  mechanical  life,  and  it  is 
therefore  regarded  as  the  ideal  preservative  and  a  standard  by  which 
all  others  must  be  gauged.  The  reason  for  this  is  due  primarily  to 
the  fact  that  time,  the  all-important  factor  in  the  field  of  wood 
preservation,  has  demonstrated  its  value  under  most  variable  and 
trying  conditions.  There  are  numerous  'well-authenticated  in- 

[  586] 


WOOD  PRESERVATION  Sec.  9 

stances  of  timber  being  preserved  by  creosote  oil  for  periods  of  time, 
in  some  cases  amounting  to  30  or  even  40  years;  a  notable  example 
being  a  Baltic  redwood  tie  removed  from  the  tracks  of  the  Glasgow 
and  Southwestern  Railway,  in  Scotland,  in  a  perfect  state  of  pres- 
ervation after  42  years  of  service.  There  still  remained  in  the  tie 
over  12  pounds  of  creosote  oil  per  cubic  foot. 

While  it  is  probable  that  the  controlling  factor  governing  the  first 
use  of  this  oil  was  that  it  could  be  obtained  in  large  quantities  at  a 
reasonable  cost,  theoretical  considerations  to-day,  based  on  our 
more  advanced  knowledge  of  the  causes  underlying  decay,  indicate 
that  the  chemical  and  physical  characteristics  possessed  by  coal-tar 
creosote  oil  make  it  well  worthy  of  the  high  esteem  in  which  it  is 
held,  and  places  beyond  the  bounds  of  probability  any  suggestion 
that  the  long  life  of  timber  treated  with  this  preservative  may  have 
been  due  to  other  causes. 

13.  Coal-Tar  Creosote.  Owing  to  its  importance  in  timber  pres- 
ervation, as  well  as  to  illustrate  the  relation  existing  between  it  and 
other  oils  now  being  used  for  this  purpose,  a  more  or  less  detailed 
description  of  the  manner  in  which  it  is  produced  may  not  be  out  of 
place. 

In  the  manufacture  of  illuminating  gas,  by  the  destructive  dis- 
tillation of  coal  in  closed  vessels,  coal-tar  is  produced  as  a  by-product. 
It  is  also  produced  as  a  by-product  in  the  operation  of  retort  coke 
ovens.  The  difference  in  the  physical  characteristics  of  the  tars 
produced  in  the  two  operations  is  so  slight  that  one  may  easily  be 
mistaken  for  the  other,  and  chemically  they  are  identical,  containing 
the  same  constituents,  but  in  somewhat  different  proportions. 

At  gas  works,  the  coal  is  carbonized  in  externally  heated  fire-clay 
retorts  capable  of  working  off  a  charge  of  from  three  to  four  hundred 
pounds  of  coal  every  four  hours,  while  at  by-product  coke  ovens 
the  charge  amounts  to  several  tons,  and  the  duration  of  the  carbon- 
izing period  may  be  from  18  to  30  hours.  This  difference  in  method 
of  carbonization  has  some  influence,  as  stated  above,  on  the  quality 
of  the  tar,  and  therefore  on  the  oils  distilled  therefrom. 

Bituminous  coal  containing  a  considerable  amount  of  volatile 
matter  is  used  in  these  operations.  That  used  in  the  manufacture 
of  gas  by  the  retort  method  may  contain  as  much  as  35  to  40  per 
cent,  while  that  used  in  coke  ovens  usually  contains  somewhat  less. 

The  residue  remaining  in  the  retort  or  oven,  as  the  case  may  be, 
constitutes  coke.  It  is  from  the  volatile  matter  which  is  driven  off 
that  illuminating  gas  and  tar  are  produced. 

This  volatile  matter  consists  of  permanent  gases,  such  as  ethylene 
and  its  homologues,  hydrogen,  marsh  gas,  carbon  monoxide,  oxygen, 
nitrogen,  etc.,  which  carry  in  suspension  vapors  of  various  other 
hydrocarbons,  whose  boiling  points  cover  a  considerable  temperature 
range.  A  slight  reduction  in  the  temperature  of  the  carrying  gas 
causes  a  partial  precipitation  of  the  suspended  hydrocarbons,  and 
since  a  gas  which  will  be  suitable  for  illuminating  purposes  must  be 
permanent  under  ordinary  conditions,  it  is  necessary  to  free  it  more 

[  587  ] 


Sec.  9 


WOOD  PRESERVATION 


or  less  completely  of  suspended  matter.  The  readiness  with  which 
the  hydrocarbon  vapors  precipitate  upon  even  a  slight  reduction  in 
temperature  is  taken  advantage  of  to  free  the  gas  of  their  presence, 
the  operation  being  assisted  by  the  use  of  condensers  and  scrubbers. 
The  condensed  liquid  is  known  as  coal-tar. 


A.  chemical  examination  of  coal-tar  shows  it  to  be  largely  made  up 
of  hydrocarbons  of  the  closed  ring  or  aromatic  series,  prominent 
among  them  being  benzol,  toluol,  xylol,  naphthalene,  carbolic  acid, 
anthracene,  etc.,  which  have  been  formed  by  the  high  heat  to  which 
the  coal  has  been  subjected.  If  the  coal  is  carbonized  at  a  low  heat, 
the  character  of  the  hydrocarbons  is  much  changed.  In  this  case, 

[  588  ] 


WOOD  PRESERVATION 


Sec.  9 


the  paraffin  series,  such  as  occur  in  petroleum  oils,  will  be  present 
in  considerable  quantities. 

It  should  be  borne  in  mind  that  the  hydrocarbons  found  in  coal- 
tar  do  not  exist  in  the  coal  as  such,  but  are  formed  by  breaking  down 
and  polymerization  of  other  hydrocarbons,  notably  of  the  paraffin 
series.  To  quote  a  well-known  authority,  "The  hydrocarbons 


produced  by  the  use  of  a  comparatively  low  temperature  are  mostly 
paraffins  (hydrocarbons  of  the  methane  series)  with  some  defines. 
At  a  higher  temperature  the  paraffins,  except  methane,  disappear, 
and  are  replaced  by  olefines — ethylene,  propylene  and  butylene. 
At  a  still  higher  temperature  acetylene  appears,  accompanied  by 

[589] 


Sec.  9  WOOD  PRESERVATION 


benzene,  CeHe.    These  are  followed  by  naphthalene,  Cio  H8,  chrysene, 
pyrene,  diphenyl,  etc." 

At  one  time  coal-tar  was  a  waste  product,  in  fact  its  accumulation 
created  a  nuisance  with  which  it  was  for  a  long  while  difficult  to  cope. 
The  discovery,  however,  by  Sir  William  Perkin,  that  some  of  its, 
constituents  could  be  used  as  bases  for  very  valuable  dyes  opened 
up  a  field  which  has  developed  along  this  and  other  lines  to  such  an 
extent  that  tar  distillation  has  become  an  important  industry,  and 
there  are  at  the  present  time  few,  if  any,  compounds  obtainable  from 
coal-tar  that  are  not  commercially  valuable. 

It  is  customary  in  the  first  distillation  of  coal-tar,  which  is  carried 
out  in  externally  fired  stills,  varying  in  capacity  from  a  few  hundred 
to  several  thousand  gallons,  to  make  a  preliminary  more  or  less 
crude  separation  of  the  volatile  portions  of  the  tar  into  several 
fractions.  The  first,  or  light  oil  fraction,  constitutes  the  raw  material 
from  which  are  obtained  benzol,  toluol,  and  solvent  naphtha.  This 
cut  is  made  at  about  170  degrees  Centigrade  (338  degrees  Fahren- 
heit). A  second  cut  at  about  230  degrees  Centigrade  (446  degrees 
Fahrenheit)  includes  the  middle  oils,  which  contain  a  large  portion 
of  the  tar  acids  and  naphthalene.  A  third  cut  at  270  degrees  Centi- 
grade (518  degrees  Fahrenheit)  includes  creosote  oil.  The  residue 
remaining  in  the  still  may  be  hard  or  soft  pitch,  depending  upon  the 
extent  to  which  the  heavier  fractions  are  removed  .  If  the  distillation 
is  carried  to  hard  pitch,  heavy  anthracene  oils  are  recovered  after 
the  creosote  oils.  The  accompanying  diagram  graphically  illustrates 
the  position  which  creosote  oil  bears  to  the  other  products  obtainable 
from  coal-tar. 

Benzol 


Coal-tar 


Light  oil 


Middle  oil 


Creosote  oil 
Anthracene  oil 
Pitch 


Toluol 
Naphthas 
Carbolic  oils 
(tar  acids) 

Naphthalene 


Commercial  Creosote 


Since  creosote  oil  is  a  mixture  of  various  oils  it  is  not,  even  under 
the  best  conditions,  of  invariable  quality,  and  under  conditions 
usually  met  with  a  uniform  grade  is  difficult  to  obtain  at  a  price 
which  would  not  be  prohibitive.  There  are  several  reasons  for  this. 
In  the  first  place,  the  carbonization  of  different  kinds  of  coal  will 
affect,  to  a  certain  extent,  the  character  of  the  tar  and  necessarily, 
therefore,  of  the  oils  distilled  therefrom.  Then  it  is  the  practice  of 
some  tar  distillers  to  carry  the  distillation  farther  than  others,  e.  g., 
it  is  the  usual  practice  abroad  to  make  hard  pitch,  which  means  that 
there  will  be  relatively  more  of  the  high-boiling  anthracene  fractions 
left  in  the  creosote  oil  than  when  soft  pitch  is  made,  as  is  the  usual 
practice  of  American  tar  distillers.  Another  factor  operating 
against  uniformity  is  that  creosote  oil  usually  commands  the  lowest 
price  of  the  oils  produced  in  a  tar  distilling  plant,  and  it  is  customary, 

[  590  ] 


WOOD  PRESERVATION  Sec.  9 

therefore,  to  extract  from  the  heavy  oil  fraction  the  products  which, 
at  the  time,  are  more  valuable  than  creosote.  It  may  happen  that 
the  demand  for  naphthalene  is  slight,  and  therefore  the  price  which 
can  be  obtained  for  it  low.  At  such  times  it  is  usually  left  in  the 
creosote  oil  and  sold  for  wood  preservation.  When  the  market  for 
naphthalene  changes  for  the  better  it  may  be  recovered,  with  the 
attendant  change  in  the  composition  of  the  creosote  oil.  It  is  a 
common  practice,  also,  to  run  residues  and  other  oils  of  relatively 
low  value  into  the  creosote  oil  tank;  in  other  words,  it  is  the  re- 
ceptacle for  the  low-grade  oils  produced  by  the  plant.  In  spite  of 
this,  the  preservative  value  of  the  oil  is  such  that  ample  protection 
against  decay  has  been  procured  when  a  sufficient  quantity  of  the 
oil  was  injected.  Owing  to  the  steadily  growing  progress  being 
made  in  the  art  of  wood  preservation  with  the  increasing  knowledge 
of  what  constitutes  the  best  grade  of  creosote  oil,  large  consumers 
are  now  purchasing  under  specifications,  with  the  object  in  view 
of  eliminating  that  portion  of  the  oil  which  will  be  lost  by  volatiliza- 
tion or  solution,  either  during  the  process  of  treatment  of  the  timber 
or  after  it  is  placed  in  service,  and  of  insuring  in  the  oil  the  amounts 
of  those  constituents  which  they  deem  most  suitable  for  their  par- 
ticular purpose.  Opinions  differ  greatly  as  to  which  are  the  most 
important  constituents  of  creosote  oil.  There  are  some  who  main- 
tain that  the  tar  acids,  which  are  germicides,  are  the  most  important 
constituents.  Others  contend  that  naphthalene  is  the  most  valu- 
able, attributing  its  efficiency  to  its  antiseptic  qualities  or  to  its 
crystallization  in  the  pores  of  the  wood,  preventing  entrance  of 
moisture  and  keeping  in  the  lighter  portions  of  the  oil.  Still  others 
claim  that  it  is  the  heavy  anthracene  oil  fractions  that  are  of  the 
most  value,  these  oils  losing  little  by  volatilization  and  solution,  and 
effectively  excluding  moisture  and  air.  Antiseptic  powers  are  also 
claimed  for  them  by  many. 

Considerable  light  has  recently  been  thrown  on  this  subject  by 
the  Forestry  Service.*  Some  forty  specimens  of  creosoted  timber 
that  had  successfully  resisted  decay  for  from  10  to  40  years  were 
examined,  and  it  was  found,  in  every  instance,  that  the  tar  acids 
had  either  disappeared  entirely  or  been  reduced  to  less  than  1  per 
cent,  and  that  the  constituents  of  the  oil  which  had  remained  in  the 
timber  represented  the  naphthalene,  anthracene,  and  other  high- 
boiling  fractions. 

The  value  of  such  oils  is  now  generally  conceded,  but  their  high 
price  restricts  their  application  for  full-cell  treatments.  These 
high-boiling  oils  constitute  in  whole,  or  in  part,  many  of  the  well- 
known  high-priced  preservatives.  When  such  oils  are  once  gotten 
into  the  wood  there  is  little  chance  of  loss  by  volatilization,  and  for 
this  reason  their  value  is  greater  than  that  of  the  ordinary  grades  of 
coal-tar  creosote.  Such  high  gravity  oils  have  their  application  in 
brush  and  dipping  treatments  referred  to  in  another  portion  of  this 
report, 

*  Bulletin  No.  98. 

[591] 


Sec.  9  WOOD  PRESERVATION 

Authorities  are  now  generally  agreed  that  the  value  of  light  oils 
and  tar  acids  is  of  minor  importance  compared  with  the  heavy 
fractions.  It  is  perhaps  safe  to  say  that  those  oils  coming  off  below 
205  degrees  Centigrade  (401  degrees  Fahrenheit),  when  distilled  by 
one  or  other  of  the  standard  methods  commonly  employed  in  this 
country  in  which  the  thermometer  indicates  the  temperature  of  the 
vapor,  will  be  lost,  either  during  treatment  or  after  the  timber  is 
put  into  service. 

14.  Water-Gas  Tar  Creosote.  While  the  value  of  other  oils  for 
wood  preservation  is  not  so  well  established  as  that  of  coal-tar 
creosote,  owing  to  the  fact  that  time  alone  can  furnish  absolute 
proof,  theoretical  and  other  considerations  point  to  the  fact  that  oils 
distilled  from  water-gas  tar  may  be  of  equal  value.  If  such  is  the 
case,  it  will  do  much  to  relieve  the  difficulty  in  securing  suitable  oils, 
since  two-thirds  of  the  gas  used  for  illuminating  purposes  in  the 
United  States  at  the  present  time  is  water-gas,  and  about  75,000,000 
gallons  of  tar  are  made  as  a  by-product  of  its  manufacture. 

On  account  of  the  well-known  preservative  value  of  coal-tar 
creosote  and  its  relatively  higher  cost,  oils  of  other  origin  are  generally 
looked  upon  as  adulterants,  and  while  the  preservative  value  of  the 
coal-tar  creosote  may  not  have  been  lessened  by  the  admixture,  the 
practice  constitutes  a  fraud  if  the  material  is  sold  as  straight  coal-tar 
creosote.  In  Bulletin  No.  78  of  the  Forest  Service,  the  following 
statement  is  made: 

"Petroleum-tar  creosote  is  already  used  in  large  quantities,  most  of 
it  being  sold  not  under  its  own  name  but  as  an  adulterant  of  coal-tar 
creosote.  It  contains  some  of  the  most  important  constituents  of 
coal-tar  creosote  as  well  as  those  of  the  paraffin  series.  Its  analysis 
by  fractional  distillation  is  sometimes  identical  with  that  of  the  coal- 
tar  product,  and  it  is  probable  that  after  injection  into  timber  it 
would  show  no  more  rapid  volatilization." 

In  this  Bulletin  no  distinction  is  made  between  water-gas  tar 
creosote  and  creosote  produced  from  tars  formed  in  the  process  of 
making  oil-gas  as  in  the  Pintsch  or  the  straight  oil-gas  systems, 
although  the  chemical  constitution  of  tars  produced  in  making  oil- 
gas  is  quite  different.  Since,  however,  very  little  of  this  tar  is  made, 
the  reference  is  undoubtedly  to  water-gas  tar. 

The  manner  in  which  water-gas  tar  is  produced  from  petroleum, 
explains  its  striking  similarity  to  coal-tar.  In  this  process  "blue 
gas, "  which  consists  of  a  mixture  of  carbon  monoxide  and  hydrogen, 
obtained  by  passing  steam  through  a  bed  of  incandescent  coal  or 
coke,  is  passed  into  a  chamber  containing  checker  brick  heated  to  a 
high  temperature.  There  it  is  carburetted  by  the  oil-gas  resulting 
from  the  cracking  up  of  petroleum  oil  which  is  fed  into  the  chamber. 
Thence  the  carburetted  gas  is  passed  into  a  second  chamber  similarly 
constructed,  and  there  subjected  to  further  heat,  which  more  or  less 
completely  finishes  the  transformation  of  the  paraffin  hydrocarbons 
contained  in  the  petroleum  oil  into  hydrocarbons  of  the  closed  ring 
or  aromatic  series  similar  to  those  found  in  coal-tar.  Naphthalene 

[592] 


WOOD  PRESERVATION  Sec.  9 

and  all  other  compounds,  except  the  oxygenated  "tar  acids,"  are 
produced;  the  production  of  these  latter  being  prevented  probably 
by  the  reducing  effect  of  the  carbon  monoxide  and  hydrogen  present 
in  the  "blue  gas."  If  the  heat  is  sufficiently  high  and  the  contact 
with  the  checker  brick  sufficiently  prolonged,  there  will  be  practically 
no  uncracked  paraffin  oil  in  the  tar,  and  this  is  likely  to  be  the 
case  in  the  best  operated  works,  because  the  presence  there  of  un- 
cracked oil  means  inefficient  and  uneconomical  operation  of  the 
machines. 

Water-gas  tar  is  now  employed  in  the  production  of  benzol,  toluol, 
solvent  naphtha,  naphthalene,  and  other  similar  compounds  here- 
tofore obtained  almost  exclusively  from  coal-tar;  and  exhaustive 
examinations  of  the  high-boiling  fractions  reveal  the  presence  of 
methyl  and  dimethyl  anthracene,  phenanthrene,  and  other  con- 
stituents found  in  coal-tar.  Owing  to  the  absence  of  tar  acids,  it 
is  impossible  to  say,  at  the  present  time,  whether  the  oil  is  a  germicide. 
It  is  an  antiseptic,  and  there  is  not  the  least  doubt  that  there  may 
be  procured  from  it  an  oil  of  high  gravity  which  should  remain 
in  the  wood-cells  indefinitely.  Such  being  the  case,  its  value  should 
be  equal  to  that  of  coal-tar  creosote. 

Owing  to  the  comparatively  short  time  in  which  this  oil  has  been 
on  the  market,  the  only  well-authenticated  test  is  of  but  three  years' 
duration.  In  this  instance  it  was  placed  in  comparison  with  coal-tar 
creosote  and  zinc  chloride  in  the  Silver  Creek  Colliery  of  the  Phila- 
delphia and  Reading  Coal  and  Iron  Company,  being  used  in  protect- 
ing mine  timbers.  At  the  present  time  there  appears  to  be  no 
difference  in  the  results  of  the  three  treatments,  all  of  the  timbers 
being  perfectly  sound,  while  the  untreated  timber  was  completely 
destroyed  in  15  months. 

The  following  statement  in  a  recent  article  written  for  the  Forest 
Service  is  also  of  interest  in  connection  with  this  oil: 

"It  is  from  the  distillation  of  water-gas  tar,  under  certain  rather 
rigid  conditions,  that  consumers  of  creosote  in  this  country  will  have 
to  look  for  increased  supplies.  Providing  that  such  creosote  is 
distilled  from  a  tar  produced  in  the  manufacture  of  illuminating  gas 
by  the  Lowe  or  similar  process,  and  from  crude  oils  containing  as- 
phalt base,  and  provided  that  the  proper  fraction  is  collected  on 
distillation,  it  very  closely  approximates  a  straight  run  coal-tar 
creosote.  The  main  difference  is  the  almost  complete  absence 
of  phenol,  cresols,  or  homologous  'tar  acids.'  The  naphthalene 
content  of  either  coal-tar  creosote  or  water-gas  dead  oil,  distilled 
under  similar  conditions,  is  generally  about  equal,  so  that  where 
(as  some  specifications  demand)  this  product  is  required,  and  the 
content  of  tar  acids  not  considered  of  importance,  either  oil  is  valu- 
able provided  the  specific  gravity  is  sufficiently  high  and  distillation 
results  satisfactory." 

Since  no  tar  acids  can  be  recovered  from  water-gas  tar  oils,  it  is 
possible  to  obtain  a  much  more  uniform  creosote  oil  from  this  tar 
than  from  coal-tar,  and  where  a  distillation  is  carried  to  coke,  as  is 
sometimes  done,  straight  run  oil  may  be  obtained  of  any  gravity 

[  593  ] 


Sec.  9  WOOD  PRESERVATION 

between  1  and  1.12  and  within  such  distillation  limits  as  to  preclude 
the  possibility  of  loss  by  evaporation. 

15.  Petroleum  Oil.     It  appears  from  the  success  met  with  on  the 
Gulf,  Colorado  &  Santa  Fe  Railroad,  in  using  crude  petroleum  for 
protecting  railroad  ties  against  decay,  that  this  oil  may  be  of  great 
value  in  wood  preservation.     A  test  was  started  in  1902,  and  the  ties 
treated  with  Bakersfield  oil,  to  the  extent  of  23  to  82  pounds  per  tie, 
are  still  in  a  good  state  of  preservation.     The  Santa  Fe  Railroad  is 
now  operating  a  tie-treating  plant  using  this  material.     It  is  probable 
that  the  oil  has  no  germicidal  action  and  that  its  value  is  dependent 
upon  the  protection  offered  against  entrance  of  moisture. 

16.  Wood  Creosote.     The  use  of  wood  creosote  for  timber  pres- 
ervation is  very  limited,  and  the  results  that  have  been  obtained 
are  of  uncertain  value,  owing  to  the  fact  that  in  the  majority  of 
cases  it  was  applied  by  the  brush  or  dipping  process  and  very  few 
records  have  been  kept. 

A  test  started  in  1905  by  the  United  States  Forest  Service,  in  the 
treatment  of  telephone  poles,  employed  wood  creosote  as  one  of  the 
preservatives.  Sufficient  time  has  not  elapsed,  however,  to  make 
any  definite  statements  with  reference  to  its  probable  value.  It  is 
possible,  however,  that  if  it  is  injected  into  the  wood  in  sufficient 
quantities  it  will  offer  adequate  protection.  Its  high  cost,  accom- 
panied with  its  unknown  value  as  a  preservative,  will,  however, 
restrict  its  use. 

The  table  on  following  page  will  show,  at  a  glance,  the  chief 
difference  between  coal-tar  creosote,  water-gas  tar  creosote,  wood 
creosote,  petroleum-tar  oil  and  petroleum  oil.  (Table  93.) 

17.  Preservation  with  Salts.    The  comparatively  small  use  being 
made  of  salts  in  the  treatment  of  poles  and  cross-arms  renders  it  un- 
necessary to  describe  these  preservatives  at  this  time,  particularly 
so  since,  being  perfectly  definite  chemical  compounds,  a  description 
of  them  may  be  obtained  from  any  chemical  dictionary  or  work  on 
inorganic  chemistry. 

18.  Summary  on  Preservatives.     The  choice  of  the  proper  pre- 
servative is  dependent,  in  a  great  measure,  upon  local  conditions. 
Full-cell  treatments,  with  a  high-grade  creosote  oil,  will  insure  the 
maximum  protection,  but  it  is  by  no  means  uncertain  that  full-cell 
treatments  with  petroleum  oil  or  other  heavy  oils  will  not  offer  an 
equal  amount  of  protection.     The  chief  danger  in  employing  such 
oil  would   lie  in  not  using  it  in  quantities  sufficient  to  keep  out 
moisture  or  air. 

It  would  seem  that  an  entirely  satisfactory  oil,  having  antiseptic 
qualities,  can  be  obtained  from  the  distillation  of  water-gas  tar,  and 
as  this  material  may  be  readily  obtained,  its  general  use  would  do 
much  toward  solving  the  difficulty  of  obtaining  suitable  oils  at  a 
reasonable  cost. 

While  from  a  theoretical  standpoint  the  use  of  metallic  salts 
cannot  be  recommended  for  poles  and  cross-arms  on  account  of 

[594] 


WOOD  PRESERVATION 


Sec.  9 


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t  595  ] 


Sec.  9  WOOD  PRESERVATION 

their  solubility,  still,  in  view  of  the  exceptional  results  obtained 
in  Germany  by  the  use  of  copper  sulphate  and  mercuric  chloride, 
it  is  impossible  to  say  that  these  cannot,  at  times,  be  used  to  great 
advantage.  It  is  recommended,  however,  when  salt  treatments  are 
employed,  that  they  be  protected  against  leaching  by  creosote  or 
some  such  similar  method,  and  also  that  due  caution  be  exercised 
in  choosing  this  method  of  treatment. 

Since  much  of  the  treating  which  will  be  done  for  the  members 
of  the  National  Electric  Light  Association  is  likely  to  be  by  the 
open-tank  process,  special  attention  should  be  paid  to  specifications 
covering  suitable  oils,  it  being  remembered  that  a  large  part  of  the 
oil  distilling  under  200  degrees  Centigrade  is  likely  to  be  lost  by 
volatilization  during  the  process  of  treatment,  thus  greatly  increasing 
the  cost.  The  oil  to  be  used  in  the  open  tank  should  constitute  the 
higher  boiling  portions  of  the  tar. 

PROCESSES 

19.  General.  There  are  several  causes  underlying  the  rapid 
development  which  has  resulted  in  the  modern,  highly  efficient 
processes  for  impregnating  timber  with  preservatives.  The  most 
important,  perhaps,  was  the  early  recognition  of  the  fact  that, 
however  great  might  be  the  value  of  a  preservative  in  retarding  or 
preventing  decay,  from  a  theoretical  standpoint,  its  practical  ef- 
ficiency was  likely  to  be  largely  dependent  upon  the  extent  to  which 
it  was  driven  into  the  timber.  For  this  reason,  the  early  methods  of 
steeping  the  timber  in  the  cold  preservative  contained  in  an  open 
tank  or  vat  was  soon  almost  entirely  superseded  by  processes  in- 
suring deeper  penetration.  Another  important  factor  underlying 
this  development  was  the  growing  demand  made  upon  commercial 
plants  for  treated  timber,  coincident  with  the  recognition  of  the 
great  economic  value  of  timber  preservation  and  the  urgent  necessity 
for  husbanding  the  diminishing  supply  of  timber  suitable  for  rail- 
road and  other  purposes. 

As  in  other  branches  of  business,  increased  demand  on  the  part  of 
the  consumer  resulted  in  increased  effort  on  the  part  of  the  treating 
plants  to  turn  out  a  maximum  amount  of  satisfactory  work  in  the 
shortest  possible  time,  while  reducing  the  cost  to  a  minimum.  The 
greatest  aid  in  the  achievement  of  this  end  has  been  the  employment 
of  artificial  pressure  in  injecting  the  fluid,  it  being  found  that  by  its 
use  deep  penetration  could  be  gotten  in  a  comparatively  short  time. 

Owing  to  the  heavy  cost  of  installing  high-pressure  systems, 
however,  there  are  comparatively  few  privately  operated  plants  in 
the  United  States,  and  for  this  reason  the  small  consumer  of  treated 
timber  must  either  purchase  from  the  large  commercial  plants, 
often  so  remote  as  to  make  the  cost  almost  or  quite  prohibitive,  or 
treat  locally  by  a  less  costly  process.  To  meet  the  demands  of  this 
class,  as  well  as  of  those  who  desire  only  a  moderate  protection  at  a 
small  cost,  the  United  States  Forest  Service  has  devoted  considerable 
time  to  the  development  of  the  open-tank  or  low-pressure  system, 
and  has  brought  its  efficiency  to  such  a  degree  that  in  many  instances 

[596] 


WOOD  PRESERVATION 


Sec.  9 


it  is  possible  to  obtain  adequate  protection  at  a  very  low  cost.  Such 
plants  can  usually  be  operated  by  unskilled  labor,  require  no  ex- 
pensive apparatus,  and  involve  a  very  small  initial  investment. 

All  processes  for  treating  timber  may  be  considered  under  three 
heads — high  artificial  pressure  systems,  the  atmospheric  pressure 
systems,  and  the  low  artificial  pressure  systems;  the  first  including 
most  of  the  commercial  plants,  the  second  and  third,  the  small 
individual  plants. 

The  following  table  contains  a  classification  of  the  most  important 
systems,  which  are  described  in  more  or  less  detail  further  on.  Some 
of  them  cannot  be  recommended  for  the  treatment  of  poles  or  cross- 
arms,  but  it  is  felt  that  the  whole  field  should  be  reviewed  as  a  matter 
of  general  interest: 

Bethell 


High     Artificial    Pressure 
Systems 


Atmospheric  Pressure  Sys- 
tem . . 


Low     Artificial 
Systems 


Pressure 


Full  Cell 

Empty  Cell 
Full  Cell 

Empty  Cell 
Full  Cell 
Empty  Cell 


Burnett 

Wellhouse 

Rutgers 

Card 

Allardyce 

Ruping 
Lowry 

Steeping  in  cold  preservatives 
Steeping  in  hot  preservatives 
Alternate  hot  and  cold  treatments 

Hot,  cold  and  hot  treatments 
Hot  and  graded  cooling  treatment 


20.  HIGH  ARTIFICIAL  PRESSURE  PROCESSES.     High-pres- 
sure processes  may  be  either  full  cell  or  empty  cell,  depending  upon 
whether  or  not  the  full  amount  of  preservative  injected  into  the  tim- 
ber is  left  in  the  cells  or  a  portion  subsequently  withdrawn.     The 
advocates  of  the  full-cell  treatments  claim  that  unless  the  full  amount 
of  the  preservative  is  left  in  the  timber,  sufficient  protection  against 
decay  will  not  be  afforded;   while  the  advocates  of  the  empty-cell 
treatments  claim  that,  provided  the  penetration  is  deep,  it  is  only 
necessary  to  leave  a  thin  coating  of  the  preservative  on  the  cell- 
walls.      Obviously,   empty-cell   treatments   result   in    considerable 
economy  of  the  preservative. 

The  most  prominent  of  the  full-cell  processes  are  the  Burnett, 
Card,  Allardyce,  Wellhouse,  and  Rutgers.  Of  the  empty-cell 
processes,  the  Ruping  and  Lowry  are  the  best  known. 

21.  Full-cell  Treatments. — Bethell.     The  best  known  of  all  pre- 
servative systems  is  the  full-cell  Bethell,  employing  straight  creosote 
as  the  preservative.     In  operating  the  Bethell  process,  the  timber 
to  be  treated  is  loaded  upon  trucks  and  run  into  a  cylinder  capable 
of  withstanding  a  high  pressure.     These  cylinders,  or  retorts,  as 
they  are  now  called,  are  sometimes  as  much  as  nine  feet  in  diameter 

[597] 


Sec.  9 


WOOD  PRESERVATION 


and  165  feet  long.  They  are  made  of  boiler  plate  and  are  provided 
with  doors  which  may  be  hermetically  sealed  and  are  tight  under  a 
high  pressure.  For  light  treatment,  the  timber  may  be  only  air 
seasoned,  but  when  a  heavy  treatment  is  desired  the  timber  is 
steamed  after  it  is  put  into  the  cylinder.  The  method  of  operation 
is  as  follows: 

After  the  doors  are  closed,  live  steam  is  admitted  and  a  pressure 


of  about  20  pounds  per  square  inch  is  maintained  for  several  hours, 
the  exact  time  depending  upon  the  individual  opinion  of  the  operator 
as  well  as  upon  the  moisture-content  and  the  size  of  the  timber  being 
treated.  In  some  cases  the  steam  pressure  is  allowed  to  go  con- 

[  598  ] 


WOOD  PRESERVATION 


Sec.  9 


siderably  above  20  pounds,  but  much  above  this  there  is  constant 
danger  of  injuring  the  timber.  When  the  steam  is  finally  blown  put 
of  the  cylinder,  a  vacuum  is  created  and  as  much  of  the  air  as  possible 
is  exhausted  from  the  cylinder  and  from  the  wood  structure.  The 
condensed  steam  and  sap  from  the  wood  are  drawn  off  at  the  same 


time.  The  exhaustion  period  varies  with  the  extent  of  the  treatment. 
Finally,  after  a  sufficient  vacuum  is  obtained,  the  creosote  oil  is  run 
into  the  cylinder  and  the  pressure  pumps  are  started  and  continued 
until  the  desired  amount  of  preservative  fluid  has  been  injected. 
The  remaining  oil  is  then  forced  back  into  the  storage  tanks.  The 
timber  is  allowed  to  drip  for  a  few  minutes  and  finally  the  cylinder 

[599] 


Sec.  9  WOOD  PRESERVATION 

doors  are  opened  and  the  treated  timber  withdrawn.  The  whole 
cycle  of  operation  takes  from  six  to  twenty  hours,  depending  upon 
the  condition  and  kind  of  timber,  size  of  treating  cylinder,  quantity 
of  injection,  etc.  As  a  rule,  it  requires  about  three  and  one-half 
hours  for  steaming,  about  one  hour  for  vacuum  and  whatever  time 
it  may  be  necessary  to  get  the  required  injection.  Figs.  345  and  346, 
show  two  views  of  pressure  treating  cylinders. 

22.  Burnett.     The  Burnett  process  is  similar  to  the  Bethell,  but, 
instead  of  using  creosote  as  the  preservative,  it  employs  a  two  to 
three  per  cent  solution  of  zinc  chloride,  which  is  injected  into  the 
timber  under  pressure  in  the  same  way.     The  use  of  zinc  chloride, 
or  "Burnettizing,"  for  treating  railroad  ties  dates  from  1850. 

23.  Wellhouse.     The  users  of  the  Wellhouse  process  claim  to 
have  overcome  the  chief  objection  to  the  Burnett  system;   namely, 
the  solubility  of  the  zinc  chloride  and  the  consequent  danger  of  its 
being  dissolved  out  of  the  timber  when  it  is  put  into  use.     To  pre- 
vent this  the  zinc  chloride  treatment  is  followed  by  an  injection  of 
glue  and  tannin,  which  forms  an  insoluble  "leather"  stopping  up 
the  wood  pores. 

24.  Rutgers.     This  is  another  method  of  preventing  the  leaching 
of  the  zinc  chloride.     A  mixture  of  zinc  chloride  and  creosote  is  em- 
ployed consisting  of  from  fifteen  to  twenty  per  cent  creosote  and  a 
three  to  four  per  cent  solution  of  zinc  chloride.     The  emulsion  is 
forced  into  the  timbers,  as  in  the  Burnettizing  and  Bethell  processes* 
This  system  is  extensively  used  in  Europe,  and  to  some  extent  in  this 
country. 

25.  Card.     This  process  substitutes  creosote  oil  for  the  glue  and 
tannin  of  the  Wellhouse  process,  it  being  claimed  that  the  oil  is 
effective  in  preventing  the  zinc  chloride  from  being  dissolved  out. 
The  chief  difference  between  this  process  and  the  Rutgers  is  that  dur- 
ing the  time  of  injecting  the  liquid  into  the  timber  the  mixture  is 
kept  in  continuous  circulation  by  means  of  a  centrifugal  pump. 
It  is  claimed  that  this  precludes  the  possibility  of  a  separation  of 
the  zinc  chloride  and  creosote,  and  insures  a  uniform  injection  of  the 
preservatives.     The  following  statement  is  made  by  the  exploiters 
of  the  Card  system  concerning  its  operation  and  efficiency : 

"In  the  zinc  creosote  or  mixed  treatment,  as  it  is  sometimes 
called,  the  light  oils,  such  as  phenols  and  cresols,  to  a  certain  extent, 
are  soluble  in  hot  water  and  are  carried  with  the  zinc  chloride  into 
the  heart-wood  of  the  timber  as  well  as  through  the  sap-wood.  The 
heavy  oils  will  not  penetrate  the  heart-wood  but  are  deposited  in  the 
sap-wood,  and  as  these  heavy  oils  are  insoluble  in  water  they  prevent 
the  zinc  chloride  from  leaching  out  of  the  timber. 

"The  two  solutions  are  kept  constantly  mixed  while  under  pressure 
by  means  of  a  centrifugal  pump  attached  to  the  treating  cylinder; 
the  suction  to  this  pump  is  connected  to  the  top  of  the  cylinder,  in 
the  middle  and  at  each  end,  and  the  discharge  from  the  pump  enters 
the  bottom  of  the  cylinder,  and  is  distributed  the  entire  length  of 

[  600  ] 


WOOD  PRESERVATION  Sec.  9 

the  cylinder  through  a  perforated  pipe.  The  mixing  device  works 
under  the  same  pressure  that  is  applied  to  the  treating  cylinder. 
The  appliance  for  mixing  the  emulsion  can  be  applied  to  any  kind 
of  cylinder,  and  is  inexpensive  in  its  first  cost,  operating  and  main- 
tenance. Since  its  installation  at  the  several  plants  now  using  the 
zinc  creosote  process,  the  contention  by  some  that  the  creosote  and 
zinc  solution  cannot  be  mixed  is  proven  to  be  without  foundation, 
as  all  samples  drawn  from  different  parts  of  the  retorts,  and  at  all 
times  during  the  process  of  treating,  show  the  oil  and  solution  to  be 
in  the  exact,  proportions  intended.  A  water  solution  of  chloride  of 
zinc  has  greater  penetrating  powers  than  creosote  oil,  and  therefore 
it  can  easily  be  injected  under  pressure  throughout  the  heart-wood 
of  timber." 

This  description  serves  well  to  illustrate  the  principles  under- 
lying the  processes  employing  the  zinc  chloride  and  creosote  com- 
bination. All  of  them  are  operated  under  the  theory  that  the  creo- 
sote will  serve  as  a  plug  to  hold  in  the  zinc  chloride. 

26.  Allardyce.    The    Allardyce    process    also  employs   creosote 
and  zinc  chloride,  but  in  this  method  of  treatment  the  zinc  chloride 
is  first  injected  and  then  followed  by  a  separate  treatment  of  creosote, 
amounting  to  about  one  to  three  pounds  per  cubic  foot. 

The  advocates  of  this  process  claim  that  inasmuch  as  the  creosote 
oil  follows  the  zinc  chloride,  a  more  effective  protection  is  offered 
against  leaching  out  of  the  salt,  the  creosote  acting  as  a  plug. 

27.  Empty-cell,  Treatment.    Riiping.     The  Riiping  process  aims 
to  secure  protection  against  decay  with  a  comparatively  small 
quantity  of  creosote.     Only  thoroughly  air-seasoned  timber  can  be 
used  in  this  process,  because  its  successful  operation  depends  upon 
compression  of  the  air  in  the  wood-cells.     The  preliminary  steaming 
and  vacuum  as  carried  out  in  the  Bethell  process  are  therefore 
omitted. 

After  the  timber  has  been  placed  in  the  cylinder  and  the  doors 
are  closed,  it  is  subjected  to  an  air  pressure  of  about  75  pounds, 
which  compresses  the  air  contained  in  the  cells.  Still  holding  this 
pressure,  the  creosote  is  forced  into  the  cylinder  at  a  higher  pressure, 
and  after  the  timber  has  been  well  covered  with  the  preservative, 
the  pressure  is  increased  to  about  225  pounds..  This  increased 
pressure  forces  the  oil  into  the  wood-cells.  Then  the  pressure  is 
released  and  the  expansive  force  of  the  compressed  air  within  the 
wood  forces  out  a  part  of  the  oil  and  leaves  merely  a  coating  of  the 
preservative  on  the  cell-walls.  The  surplus  oil  is  then  run  back  into 
the  storage  tank.  The  expulsion  of  the  surplus  oil  may  be  increased 
by  a  vacuum  in  the  treating  cylinder. 

28.  Lowry.  As  in  the  Riiping  process,  the  timber  is  seasoned  before 
treatment,  but  no  compressed  air  is  employed  in  injecting  the  preser- 
vative.    As  soon  as  the  cylinder  is  closed,  the  oil  is  admitted  and 
forced  into  the  timber  by  pressure.     Then  the  oil  is  run  out  of  the 
cylinder,  and  a  high  vacuum  is  quickly  drawn.     It  is  claimed  that 

[  601  ] 


Sec.  9  WOOD  PRESERVATION 

the  sudden  expansion  of  the  air,  which  has  been  compressed  in  the 
wood-cells,  drives  out  the  surplus  oil,  and  that  a  deep  penetration 
but  light  treatment  is  thereby  given  to  the  timber. 

29.  ATMOSPHERIC  PRESSURE  PROCESSES.     It  is  possible 
by  means  of  some  of  the  modifications  of  the  atmospheric  or  low- 
pressure  systems  to  effect  full-cell  or  empty-cell  treatment  as  in  the 
high-pressure  systems.     Such  treatments  cannot  be  given  with  the 
same  degree  of  facility  or  with  the  same  effectiveness  as  with  the 
high-pressure   systems,  but  in  many  instances  the  treatment  is 
adequate. 

30.  Full-cell  Treatments. — Steeping  in  Cold  Preservative.     The 
simplest  form  of  non-pressure  full-cell  treatments,  if  such  a  term  can 
be  applied  to  a  process  usually  giving  only  superficial  treatment,  is 
the  cold-steeping  or  soaking  process  extensively  employed  in  the  early 
days  of  wood  preservation  and  used  to  some  extent  at  the  present 
time. 

The  timber  to  be  treated  is  placed  in  an  open  vat  and  covered 
with  the  cold  solution,  which  may  be  mercuric  chloride,  zinc  chloride, 
copper  sulphate,  or  creosote  oil,  as  the  case  may  be.  In  using 
mercuric  chloride,  it  is  necessary  to  employ  non-metallic  steeping 
pits  on  account  of  the  corrosive  action  of  the  mercury.  This  treat- 
ment has  proven  very  effective  in  preserving  timber,  though  in  this 
country  its  use  for  line  timber  has  been  confined  almost  entirely  to 
the  New  England  States,  where  some  electric  companies  use  kyanized 
cross-arms.  (In  the  Appendix  will  be  found  a  report  of  the  German 
.Government's  Telegraph  Department,  wherein  very  favorable 
mention  is  made  of  the  mercuric  chloride  treatment.) 

31.  Hot  or  Boiling  Treatments.     Timber  is  sometimes  treated 
by  simply  boiling  it  in  the  preservative  contained  in  an  open  tank 
or  closed  retort  for  varying  lengths  of  time.     The  preservative  most 
commonly  used  in  this  process  is  a  heavy  creosote  oil.     The  Forest 
Service  reports  that  the  following  method  is  used  on  the  Pacific 
coast  for  Douglas  fir,  which  is  an  exceedingly  difficult  wood  to  treat. 
The  timber,  usually  green,  is  placed  in  a  treating  cylinder  containing 
creosote  heated  to  a  temperature  slightly  above  the  boiling  point  of 
water.     This  hot  bath  is  continued  for  a  time  varying  from  several 
hours  to  two  days  or  more.     The  duration  of  treatment  depends 
upon  the  size  and  condition  of  the  timber.     During  the  bath  much  of 
the  water  contained  in  the  sap  is  driven  off  together  with  the  volatil- 
ized light  oils.     These  vapors  are  caught  in  a  condenser,  the  water 
separated,  and  the  oil  then  run  back  into  the  receiving  tank  to  be 
used  over  again.     Finally,  an  oil  pressure  of  from  100  to  125  pounds 
is  applied,  and  at  the  same  time  the  temperature  of  the  oil  is  allowed 
to  fall,  thus  forcing  the  preservative  into  the  timber.     This  practice 
is  subject  to  the  general  objection  that  it  is  unwise  to  treat  timber 
before  it  has  had  time  to  dry  out  in  the  open  air. 

It  is  evident  that  the  efficiency  of  the  process  is  much  enhanced 
by  the  final  application  of  pressure,  and  that  simply  boiling  in  an 
open  tank  is  very  unsatisfactory  and  inefficient. 

[  602  ] 


WOOD  PRESERVATION 


Sec.  9 


[603] 


Sec.  9 


WOOD  PRESERVATION 


FIG.  348. — Butt  treatment  of  poles  in  open  tank. 
[  604  ] 


WOOD  PRESERVATION  Sec.  9 

32.  Alternate  Hot  and  Cold  Treatment.  This  process  is  usually 
carried  out  in  an  open  tank,  and  it  is  the  one  generally  known  as  the 
" Open-Tank  System."  However,  in  some  situations  it  has  been 
found  advisable  to  employ,  in  carrying  out  the  process,  a  low,  arti- 
ficial pressure,  which  necessitates,  of  course,  a  closed  tank  or  retort. 
The  wood  is  first  treated  with  oil  brought  to  a  temperature  of  from 
180  to  220  degrees  Fahrenheit,  for  a  sufficient  length  of  time  to  heat 
the  wood  uniformly  to  the  temperature  of  the  preservative.  It  is 
then  either  changed  to  another  bath  containing  cold  preservative 
or  the  hot  preservative  is  drawn  out  and  replaced  by  a  charge  of  cold 
preservative  at  or  below  atmospheric  temperature ;  or  the  timber  may 
be  allowed  to  remain  in  the  heated  oil,  heating  being  stopped  and  the 
oil  permitted  to  cool  down.  The  theory  underlying  the  successful 
operation  of  any  of  these  modifications  is  that  the  preliminary 
heating  expands  the  air  in  the  wood-cells,  and  when  the  cold  oil  is 
introduced  the  sudden  contraction  creates  a  partial  vacuum  which 
draws  in  the  oil.  In  some  instances,  exceedingly  good  penetration 
has  been  obtained  by  this  method,  but  it  is  not  applicable  to  all 
classes  of  wood,  owing  to  variations  in  their  penetrability. 

The  simplest  equipment  for  the  treatment  of  poles  and  cross-arms 
by  the  open-tank  method  consists  of  a  tank,  about  eight  feet  deep, 
set  high  enough  above  the  ground  to  permit  of  a  fire  beneath  it. 
Facilities  should  be  provided  for  the  convenient  handling  of  the 
poles.  Where  steam  is  available,  it  may  be  used  to  advantage  to 
heat  the  liquid  by  means  of  a  coil  in  the  tank,  and  also  to  operate 
a  hoisting  engine  for  handling  the  poles.  The  liquid  may  be  pumped 
from  the  treating  tank  to  make  room  for  the  cold  oil  to  be  introduced 
from  another  tank,  or  two  treating  tanks  may  be  employed,  one  for 
the  hot  treatment  and  one  for  the  cold.  In  connection  with  its 
California  experiments,  the  Forest  Service  described  a  pole-treating 
plant  having  a  capacity  of  120  poles  per  day,  which  was  estimated 
to  cost  between  four  and  five  thousand  dollars;  or  a  plant  with  a 
capacity  of  fifty  poles  per  day,  estimated  to  cost  two  thousand 
dollars.  The  latter  equipment  was  to  consist  of  one  12,000-gallon 
iron  storage  tank,  two  5  ft.  X  5  ft.  X  8  ft.  treating  tanks,  one  60-ft. 
mast  with  16-ft.  boom  derrick,  a  small  hoisting  engine,  a  20-hp. 
boiler,  steam  coils  for  heating  the  treating  tank,  and  one  steam  oil 
pump,  capacity  2,000  gallons  per  hour. 

Fig.  347  shows  a  view  of  the  treating  plant  of  the  Philadelphia  and 
Reading  Coal  and  Iron  Co.,  where  a  closed  retort  is  used  for  treating 
mine  timber,  but  which  could  be  utilized  for  treating  poles  and  cross- 
arms.  In  this  arrangement,  the  timber  is  run  into  a  cylinder  on 
small  buggies,  and  the  doors  are  then  closed  and  sealed  as  in  the 
high-pressure  system.  Steam  coils  heat  the  preservative  to  220 
degrees  Fahrenheit.  After  the  hot  bath,  which  is  continued  ac- 
cording to  the  condition  and  size  of  the  wood,  the  hot  preservative 
is  drawn  off  to  the  lower  tank.  Cold  oil  or  zinc  chloride  is  then 
introduced  into  the  treating  cylinder  from  the  storage  tank.  A  small 
pump  is  used  to  pump  the  oil  back  to  the  storage  tank  and  some- 
times this  pump  is  employed  to  prcduce  a  low  pressure  in  the 

[  605  ] 


Sec.  9 


WOOD  PRESERVATION 


treating  cylinder.  Fig.  348  shows  a  view  of  a  simple  open-tank 
outfit  for  treating  poles;  and  Fig.  349  gives  an  extremely  simple 
form  of  experimental  open  tank. 


FIG.  349. — A  very  simple  form  of  experimental  open  tank. 

The  most  interesting  and  useful  data  found,  regarding  open- 
tank  treatments  have  been  obtained  from  the  reports  of  the  Forest 
Service  in  connection  with  its  California  experiments  with  western 
yellow  pine  and  western  red  cedar.  (Part  III.) 

[  606] 


WOOD  PRESERVATION 


Sec.  9 


33.  Empty-cell  Treatment.— Open  Tank.  In  the  full-cell  treat- 
ment with  creosote  oil,  the  timber  is  removed  from  the  tank  with  a 
considerable  amount  of  oil  on  its  surface.  This  is  objectionable, 
not  only  on  account  of  the  waste  of  oil,  but  also  because  of  the  sub- 
sequent dripping  of  the  oil  from  the  poles  and  cross-arms  after  they 
have  been  installed.  This  difficulty  is  said  to  be  overcome  by  taking 
a  third  step  in  the  open-tank  treatment  before  described.  Before 
removing  the  timber,  after  the  cold  bath,  it  is  reheated  to  200  degrees 
Fahrenheit,  for  a  period  of  from  two  to  three  hours.  The  same  result 


FIG.    350. — Untreated  cedar  pole   decayed    at  ground  lii 
and  upward  about  two  feet. 


may  be  accomplished  by  taking  the  timber  out  of  the  bath  in  the 
second  stage  of  the  process,  after  the  creosote  has  cooled  down 
through  a  range  of  20  degrees  Fahrenheit.  This  causes  the  contract- 
ing air  in  the  wood  to  draw  in  the  free  oil  from  the  surface.  This 
method  gives  about  the  same  penetration  as  the  full-cell  open-tank 
process,  but  saves  a  considerable  quantity  of  oil,  and,  moreover, 
leaves  the  surface  of  the  wood  dry. 

34.  LOW  ARTIFICIAL  PRESSURE  SYSTEMS.— Full-  or  Empty- 
cell  Treatments.   The  Forest  Service  has  recently  endeavored  to  com- 

[  607] 


Sec.  9 


WOOD  PRESERVATION 


bine  the  advantages  of  both  the  pressure  and  non-pressure  processes 
in  a  low-pressure  system.  The  seasoned  timber  is  first  treated  in  a 
hot  bath,  as  in  the  non-pressure  treatment,  then  it  is  subjected  to 
a  cold  bath;  but,  instead  of  depending  entirely  upon  the  atmos- 
pheric pressure  to  force  the  preservative  into  the  wood,  some  arti- 
ficial pressure  is  also  applied.  The  low-pressure  process  cannot, 
of  course,  be  used  with  an  open  tank,  and  requires,  preferably,  a 
closed  cylinder,  as  in  high-pressure  work.  The  advantage  claimed 


FIG.  351. — Untreated  chestnut  pole  showing  falling  off  of  sap-wood. 

for  this  method  is  that  it  requires  much  less  time  for  treatment 
than  in  the  open  tank,  and  a  greater  absorption,  and  a  deeper  and 
more  uniform  penetration  are  secured. 

35.  MISCELLANEOUS  TREATMENTS.  — Brush  Treatments. 
Applying  the  preservative  by  means  of  a  brush  is  the  most  common, 
but  the  least  efficient,  of  all  treatments.  For  good  results  it  is  essential 
that  the  timber  be  thoroughly  seasoned,  and  that  the  wood  be  dry 
at  the  time  of  treatment.  The  preservative  is  usually  kept  heated 
to  about  200  degrees  Fahrenheit  and  is  applied  to  the  wood  with  a 
suitable  brush.  Care  should  be  taken  to  fill  all  checks,  knot-holes, 

[  608  ] 


WOOD  PRESERVATION 


Sec.  9 


and  abrasions.  A  second  coat  should  be  applied  after  an  interval 
of  not  less  than  twenty-four  hours.  Besides  treating  the  butt  of 
the  pole,  the  roof  of  the  pole  and  cross-arm  gains  should  not  be  over- 
looked, as  such  cuts,  if  left  unprotected,  expose  the  interior  to  decay. 
Some  companies  report  that  they  apply  the  preservative  with  a 
spraying  machine,  claiming  it  lias  decided  advantages  over  the  brush 
method  in  that  it  requires  less  labor  and  better  fills  all  cracks. 


FIG.  352. — Cedar  pole  coated  with  tar.     Four  year  service  all  sap-wood 
decayed  to  the  ground. 

Figs.  350  and  351  illustrate  how  the  sap-wood  may  scale  from  poles, 
leaving  the  untreated  interior  exposed  to  decay.  Such  scaling,  or 
mechanical  injury  from  various  causes,  even  the  spur  holes  made 
by  linemen's  climbing  irons,  will  defeat  the  object  of  brush  treat- 
ments. Fig.  352  shows  a  cedar  pole  after  four  years'  service,  which 
had  been  treated  with  tar.  All  of  the  sap-wood  is  decayed  to  the 
ground  line  and  is  loose  to  a  height  of  three-and-a-half  feet.  Paint- 

20  [  609  1 


Sec.  9 


WOOD  PRESERVATION 


ing  or  coating  poles  with  tar  is  not  so  generally  practiced  now  on 
account  of  the  increasing  appreciation  of  its  uselessness,  though  a 
few  years  ago  it  was  a  very  common  practice.  In  contrast  to  the 
untreated  chestnut  pole  shown  in  Fig.  353,  the  condition  of  the  pole 
shown  in  Fig.  354  should  be  noted.  This  is  a  pressure-creosoted  pine 
pole  which  has  been  in  service  near  Norfolk,  Va.,  for  eighteen  years, 
and  there  is  no  sign  of  decay.  Fig.  355  shows  a  cross  section  of  a 
well-treated  creosoted  pine  pole. 


FIG.  353. — Untreated  chestnut  pole  decayed  at  ground  line. 

36.  Brush  Combined  with  Open  Tank.     A  combination  of  open- 
tank  and  brush  treatments  is  made  by  first  treating  the  timber  with 
zinc  chloride  in  an  open  tank,  then  giving  it  one  or  more  brush 
applications  of  creosote  or  heavy  tar  oil. 

37.  Jacket  or  Butt  Settings.     Poles  are  sometimes  set  in  shells  of 
concrete.     It  is  questionable  whether  this  preserves  the  pole  other 
than  in  a  mechanical  way  by  giving  greater  stability.     When  the 

[610] 


WOOD  PRESERVATION 


Sec.  9 


concrete  hardens,  it  contracts  and  may  leave  a  space  around  the  pole, 
where  moisture  may  collect  and  cause  the  wood  to  decay.  Some 
operators  surround  the  pole  with  a  heavy  band  of  pitch  or  tar.  This 
is  not  as  desirable  as  the  concrete,  because  it  does  not  add  to  the 
mechanical  strength  of  the  pole  setting,  and  has  been  known  to 
create  rather  than  to  prevent  decay. 

Mention  may  be  made  here  of  a  patented  process  making  use  of  a 
jacket  of  asbestos  and  asphaltum  placed  around  and  at  one  or  two 


FIG.  354. — Pressure  creosoted  pine  pole — 18  years'  service  under  southern 
climatic  conditions.     No  decay  to  date. 

inches  from  the  pole  near  the  ground  line.  The  jacket  has  a  cement 
bottom  and  is  filled  with  a  mixture  of  hydrated  lime,  chloride  of 
sodium,  copper  sulphate  and  sand.  Over  the  top  of  the  jacket  and 
surrounding  the  pole  a  reinforced  cement  cap  is  placed.  It  is  claimed, 
that  the  chemicals  are  held  in  a  tight  compartment,  from  which 
they  are  slowly  dissolved  and  drawn  into  the  pole. 

Such  descriptions  might  be  continued  indefinitely  until  the  simplest 

[611] 


Sec.  9 


WOOD  PRESERVATION 


form  of  pole  preservation  or  butt  reinforcement  were  reached,  such 
as  the  method  employed  by  a  large  telephone  company,  which  may 
be  described  as  follows:  When  the  pole  butts  are  found  to  be  in  a 
fairly  advanced  stage  of  decay,  a  stub,  having  about  the  same 
dimensions  as  the  pole  butt,  is  placed  in  the  ground  alongside  of  the 


pole.  This  stub  is  long  enough  to  extend  from  the  bottom  end  of 
the  pole  to  a  point  about  two  feet  above  the  ground  line.  It  is 
secured  to  the  pole  butt  and  to  the  pole  above  the  ground  either  by 
wrappings  of  heavy  wire  or  by  through  bolts,  or  a  more  stable  job 
may  be  made  by  combined  wrapping  and  bolting.  This  plan  could 

[612] 


WOOD  PRESERVATION  Sec.  9 

scarcely  be  carried  out  under  city  or  town  conditions,  as  the  unsight- 
liness  of  the  stub  would  be  a  serious  objection,  but  it  might  be  fol- 
lowed successfully  on  trunk  lines  which  pass  through  sparsely  settled 
territory.  There  seems  no  reason  why  the  upper  part  of  poles, 
particularly  of  the  harder  species  of  wood,  should  not  be  used  in- 
definitely, provided  always  that  the  butt  reinforcement  is  made  as 
strong  and  reliable  as  would  be  the  continuous  pole. 


[613] 


SECTION  9 

PRESERVATIVE  TREATMENT  OF  POLES 
AND  CROSS-ARMS 


PART  II 
RECOMMENDED  PRACTICE  AND   SPECIFICATIONS 


SECTION  9 

PRESERVATIVE  TREATMENT  OF  POLES 
AND  CROSS-ARMS 

PART  II— RECOMMENDED  PRACTICE  AND 
SPECIFICATIONS 


TABLE  OF  CONTENTS 

ARTICLE 

General 1 

Preservatives 

General 2 

Choice  of  Preservatives 3 

Specifications 4 

A — Specifications  for  Coal-Tar  Creosote 5 

B — Specifications  for  Mixed  Oils 6 

C — Specifications  for  Water-Gas  Tar  Creosote 7 

Auxiliary  Specifications 8 

Specifications  Covering  Oil  for  Brush  Treatments 9 

Treatments 

General 10 

Pressure  System 11 

Creosoted  Pine  Poles 12 

Creosoting  of  Poles 13 

Creosoted  Pine  Cross-arms 14 

Creosoting  of  Pine  Cross-arms ~. 15 

Open  Tank  System 16 

Open  Tank  Treatment  of  Pole  Butts 17 

Description  of  Open  Tank  Plants .  . 18 

Brush  Treatments .  .                     19 


[617] 


SPECIFICATIONS  FOR  PRESERVATIVES  AND  METHODS 
OF  TREATMENT 

1.  GENERAL.     The  following  data  have  been  compiled  from  the 
1911  report  of  the  committee  on  the  preservative  treatment  of  poles 
and    cross-arms,  and   contain  only  the  recommended  specifications 
for  preservatives,  preservative  methods  and  apparatus. 

PRESERVATIVES 

2.  General.    The  subject   matter    contained    in  Part  I,  while 
serving  well  the  purpose  of  describing  the  nature  of  preservatives 
commonly  employed  in  protecting  timber  from  decay  and  the  most 
common  methods  of  examination,  contains  little  in  the  way  of 
definite  recommendations  but  is  included  in  order  to  present  to  the 
members  of  the  Association,  few  of  whom  have  any  knowledge  of 
the  subject,  information  of  a  more  or  less  general  nature  emanating 
from  recognized  authorities,  without  attempting  to  reconcile  con- 
flicting views  or  do  more  than  weed  out  the  obviously  bad  from  the 
obviously  good,  so  that  the  final  recommendations  as  contained 
herein  would  meet  the  special  needs  of  the  National  Electric  Light 
Association. 

Having  the  foregoing  in  mind,  radical  departures  from  established 
methods  were  found  necessary,  but  the  recommendations  have  been 
prepared  having  as  their  object,  to  which  all  else  was  secondary,  the 
following: 

a.  The  choice  of  the  best  preservative  for  the  protection  of  poles 
and  cross-arms  obtainable  at  a  cost  commensurate  with  its  service. 

b.  Specifications  which,  while  fully  covering  the  requirements  of 
a  high-grade  preservative,  would  at  the  same  time  be  fair  to  the 
manufacturer  and  provide  a  material  no  more  expensive  than  the 
best  grades  now  on  the  market. 

c.  A  method  of  analysis  which  would  insure  compliance  with  the 
specifications. 

3.  Choice  of  Preservatives.     Coal-tar  creosote  being  well-known 
as  a  timber  preservative,  and  its  value  as  such  being  established 
beyond  question,  is  on  this  account  recommended  by  the  committee 
as  the  standard  preservative. 

Under  certain  circumstances  it  has  been  found  advisable  to  use 
mixtures  of  coal-tar  creosote  and  various  other  tar  products.  The 
circumstances  under  which  the  use  of  such  mixtures  are  warranted 
will  depend,  to  a  large  extent,  upon  the  cost  of  the  various  oils  and 
tar  products  and  the  conditions  under  which  they  are  to  be  used. 
The  admixture  of  certain  tars  to  coal-tar  creosote  has  been  found 
particularly  advisable  where  the  latter  is  of  low  gravity,  and  also 
where  a  cheaper  preservative  could  be  obtained  by  using  such  a 
mixture  than  by  the  use  of  straight  coal-tar  creosote.  Water-gas 

[  619] 


Sec.  9  WOOD  PRESERVATION 

tar  and  products  obtained  by  the  distillation  of  water-gas  tar  nave 
been  used  for  some  years,  but  records  of  service  of  timbers  treated 
with  these  substances  are  either  not  of  sufficient  duration  or  of 
sufficient  authenticity  to  warrant  definite  conclusions  to  be  drawn 
as  to  their  value.  In  view  of  the  fact,  however,  that  considerable 
quantities  of  water-gas  tar  and  distillates  are  available  for  use  as 
timber  preservatives  and  are  being  offered  commercially,  the  com- 
mittee has  drawn  up  specifications  covering  these  latter  materials, 
as  well  as  for  coal-tar  creosote  and  for  mixed  oils.  (See  Specifications 
A,  B  and  C.) 

4.  Specifications.  Existing  specifications  for  the  purchase  of 
creosote  oil,  which  are  in  general  use,  do  not  fully  meet  the  present 
requirements,  since  it  is  possible,  even  under  the  most  stringent  of 
them,  for  unscrupulous  manufacturers  to  adulterate  and  sell  as  pure 
distilled  creosote  mixtures  with  other  materials.  Since  such  adul- 
terations are  usually  made  to  cheapen  the  cost  of  the  oil,  it  renders 
mutually  honest  competition  impossible  and  defrauds  the  purchaser 
who  is  entitled  to  receive  what  he  has  ordered  and  for  which  he  has 
paid. 

It  is  not  intended  to  imply  that  it  is  impossible  to  obtain  a  pure 
creosote,  and  often  so-called  adulterated  oils  are  knowingly  pur- 
chased and  used  with  the  consent  of  the  purchaser  of  the  treated 
timber,  but  it  is  a  well-known  fact  that  the  protection  offered  by 
strict  specifications  and  a  method  of  analysis  which  will  enforce 
them  is  at  times  needed,  and,  therefore,  the  specifications  drawn  up 
which,  while  offering  no  hardship  to  the  honest  producer,  will  insure 
the  receipt  of  an  oil  such  as  was  desired  by  the  purchaser. 

The  specifications,  which  are  offered  as  covering  three  kinds  of 
creosoting  material,  have  followed,  as  closely  as  was  deemed  ad- 
visable by  the  committee,  the  well-known  specifications  known  as 
the  "American  Railway  Engineering  and  Maintenance-of-Way 
Specifications,"  the  chief  difference  being  the  addition  of  certain 
tests  which  would  more  certainly  tend  to  indicate  adulteration,  and 
the  adoption  of  a  flask  instead  of  the  retort  for  making  the  distilla- 
tion test.  The  chief  reason  for  this  radical  step  is  that  it  was  the 
general  opinion  that  it  would  be  much  easier  to  enforce  the  speci- 
fications when  a  flask  was  used  than  when  using  the  retort,  for  the 
reason  that  retorts  of  a  uniform  size  and  shape  are  difficult  to  obtain, 
and  a  slight  change  in  the  position  of  the  thermometer,  which  is 
placed  in  reference  to  the  surface  of  the  oil,  would  give  widely  dif- 
ferent results,  and  also  on  account  of  the  difficulty  experienced  in 
placing  the  thermometer  exactly  one-half  inch  above  the  surface  of 
the  oil. 

It  is  generally  admitted  by  chemists  that  the  retort  is  an  anti- 
quated piece  of  apparatus,  and  that  it  would  be  best  to  adopt  the 
most  scientific  methods  available.  It  has  been  urged  by  some,  who 
favored  the  adoption  of  the  retort  method  of  distillation  and  the 
maintenance-of-way  specifications  in  their  entirety,  that  any  change 
in  method  would  introduce  confusion  in  the  creosoting  industry. 

[620] 


WOOD  PRESERVATION  Sec.  9 

This  argument  is  not  tenable,  provided  a  proper  relation  is  established 
between  the  results  obtained  by  the  two  methods  of  distillation. 
The  results  obtained  by  the  flask  method  of  distillation  herein 
recommended  are  practically  the  same  as  those  obtained  by  the 
retorted  method  of  distillation. 

Three  specifications  for  creosote  are  offered:  Specification  "A" 
is  designed  to  insure  the  furnishing  of  a  high  grade  of  coal-tar  creo- 
sote. Any  oil  conforming  to  this  specification  will  include  all  the 
qualities  that  would  ordinarily  be  required  in  preservative  work, 
and  the  conditions  of  the  specification  enable  the  manufacturers  or 
agents  to  make  such  an  oil  a  commodity  as  easily  available  to  the 
purchaser  or  user  as  are  other  grades  of  creosote.  For  these  reasons 
such  an  oil  as  the  standard  preservative  has  been  adopted. 

Where  circumstances  warrant  the  admixture  of  certain  tars  to 
coal-tar  creosote,  Specification  "B"  is  suggested.  (See  text  ac- 
companying specification  for  explanation  of  conditions  under  which 
the  use  of  such  a  preservative  might  be  warranted.) 

Where  water-gas  tar  creosote  is  used,  Specification  "C"  is  sug- 
gested. (See  text  accompanying  specification  for  further  remarks 
concerning  this  preservative.) 

5.  "A"  SPECIFICATIONS  COVERING  COAL-TAR  CREOSOTE 

OIL  AND  METHODS  OF  ANALYSIS 

SECTION  1— SPECIFICATION 

DEFINITION.  The  material  required  under  these  specifications 
is  that  commonly  known  as  dead  oil  of  coal  tar  or  coal-tar  creosote. 
More  specifically  defined  it  is : 

(a)  A  distillate  from  the  tar  produced  as  a  by-product  in  the 
manufacture  of  coal  gas  from  bituminous  coal  by  the  retort  method, 
or 

(b)  A  distillate  from  the  tar  produced  as  a  by-product  in  the 
manufacture  of  coke  from  bituminous  coal  by  the  by-product  coke- 
oven  process, 

or 

(c)  A  distillate  obtained  from  a  mixture  of  the  above  mentioned 
tars, 

or 

(d)  A  product  obtained  by  mixing  distillates  from  the  above 
mentioned  tars. 

It  is  understood  that  the  presence  of  any  hydrocarbons  other 
than  the  above,  either  in  the  original  tars  or  in  the  distillates  there- 
from, will,  by  defeating  the  purpose  of  this  specification,  which  is 
to  secure  a  pure  distilled  oil  from  coal  gas  or  coke-oven  tar,  be  looked 
.  upon  as  an  adulteration,  which  may  result  in  the  rejection  of  the  oil. 
As  further  defining  the  material  required,  the  hydrocarbons  specif- 
ically provided  against  include  the  following: 

(e)  Raw  or  partly  distilled  tars  or  petroleum  oils  of  any  description 
whatsoever,  such  as  coal  tar,  coke-oven  tar,  water-gas  tar,  oil  tar, 

[621] 


Sec.  9  WOOD  PRESERVATION 

lignite  tar,  blast-furnace  tar,  producer  tar,  wood  tar,  and  crude  petro- 
leum. 

(f)  Distillates  from  any  of  the  above  mentioned  tars  or  oils, 
except  distillates  from  coal  tar  and  coke-oven  tar 

(g)  Residues  from  any  of  the  above  mentioned  tars  or  oils. 

(h)  Products  obtained  by  nitration  of  any  of  the  above  mentioned 
tars  or  oils 

The  purchaser  of  the  treated  timber,  or  his  representative,  shall 
have  the  right  to  take  samples  of  the  oil  from  the  oil  tanks  or  from 
the  treating  cylinders  at  the  treating  plant  and  to  test  such  samples 
whenever  or  wherever  desired.  The  oil  may  be  refused  upon  satis- 
factory evidence  that  it  does  not  conform  to  the  specifications. 

In  the  event  of  a  dispute  between  the  purchaser  of  the  treated 
timber  and  the  firm  treating  the  same,  the  matter  shall  be  referred 
to  a  referee  mutually  agreed  upon  by  a  representative  of  the  pur- 
chaser and  the  manufacturer,  and  the  decision  of  the  referee  shall 
be  binding  and  final. 

Information,  as  complete  as  possible,  shall  be  furnished  to  the 
purchaser  upon  request  as  to  the  origin  and  history  of  the  oil. 

The  oil  required  under  these  specifications  must,  in  addition  to 
being  of  satisfactory  origin,  possess  certain  physical  and  chemical 
characteristics,  and  in  order  to  insure  that  the  sample,  which  is  used 
in  determining  these  characteristics,  correctly  represents  the  bulk 
of  the  material  from  which  it  is  taken,  the  following  rules  for  taking 
samples  must  be  observed : 

SAMPLING.  A  one-gallon  sample  of  the  oil  shall  be  taken  for 
analysis,  the  manner  of  collecting  the  same  depending  upon  the 
nature  of  storage.  The  oil  must  be  completely  liquid  when  the 
sample  is  taken,  and  it  may  therefore  be  necessary  to  heat  the  tank 
or  other  receptacle  in  which  it  is  contained.  The  following  general 
rules  shall  be  observed  when  sampling  from: 

(a)  Tank  Boat.     The  sample  shall  be  taken  from  the  pumping 
system  while  discharging  from  the  boat  into  the  receiving  tank  as 
follows:  A  half -inch  cock  shall  be  placed  in  the  line  at  any  convenient 
point  and  a  continuous  stream  of  oil  drawn  through  this  cock  during 
the  entire  time  of  emptying  the  boat.     The  rate  of  flow  of  the  stream 
should  be  proportionate  to  the  rate  of  flow  of  the  oil  in  the  pumping 
line  and  it  should  be  such  that  a  gallon  sample  may  be  collected  from 
each  10,000  gallons  of  oil  passing  through  the  pipe.     The  bulk 
sample  thus  obtained,  which  may  be  caught  in  a  barrel  or  other 
suitable  receptacle  provided  for  the  purpose,  shall  be  thoroughly 
mixed  and  shall,  if  necessary,  be  heated  to  bring  into  solution  any 
material  which  may  have  crystallized  out.      A  one-gallon  sample 
shall  be  taken  from  this  for  analysis. 

(b)  Storage  Tanks  less  than  Twenty  Feet  in  Depth.    In  sampling 
from  storage  tanks  of  less  than  twenty  feet  in  depth,  a  "thief"  shall 
be  employed.     It  shall  be  made  of  a  length  of  one-half  inch  pipe  and 
provided  at  the  lower  end  with  a  lever  handle  cock  having  an  opening 
of  approximately  the  same  size  as  the  interior  of  the  pipe.     This 
cock  being  open,  the  "thief"  is  lowered  slowly  into  the  tank  and 

[  622  ] 


WOOD  PRESERVATION  Sec.  9 

when  it  has  touched  bottom,  the  cock  is  closed  by  means  of  a  chain, 
wire,  or  iron  rod  carried  to  the  top  of  the  pipe.  A  sufficient  num- 
ber of  samples  thus  procured  shall  be  taken  to  aggregate  one 
gallon. 

(c)  Storage  Tanks  over  Twenty  Feet  in  Depth.    Samples  shall 
be  taken  from  such  tanks  through  one-half  inch  cocks  placed  one 
above  the  other  and  one  foot  apart  on  the  side  of  the  tank.     One 
gallon  of  oil  shall  be  withdrawn  from  each  level,  and  the  bulk  sample 
thus  obtained  shall  be  thoroughly  mixed  as  in  (a)  and  the  final 
sample  taken  from  this. 

(d)  Tank  Cars.     Drip  samples  shall  be  taken  from  tank  cars  as 
in  (a). 

(e)  Treating  Cylinders.    Samples  from  treating  cylinders  shall 
be  taken  from  the  charging  and  discharging  line  as  in  (a). 

PHYSICAL  AND  CHEMICAL  CHARACTERISTICS.     The  oil  under 
these  specifications  must  have  the  following  characteristics : 

1.  It  shall  have  a  specific  gravity  of  at  least  one  and  three-hun- 
dredths  (1.03)  and  not  more  than  one  and  eight-hundredths  (1.08) 
at  thirty-eight  degrees  Centigrade  (38°  C.).     If  the  gravity  is  taken 
at  a  higher  temperature,   a  correction  of  eight  ten-thousandths 
(.0008  )for  each  degree  Centigrade  above  thirty-eight  (38)  shall  be 
made. 

2.  There  shall  be  not  over  one  per  cent  (1%)  of  residue  insoluble 
in  hot  benzol. 

3.  The  original  oil  shall  contain  not  over  two  per  cent  (2%)  of 
water. 

4.  The  oil  shall  be  miscible  in  absolute  alcohol,  volume  for  volume. 

5.  The  residue  remaining  upon  sulphonating  a  portion  of  the 
total  distillate  shall  not  exceed  one  per  cent  (1%). 

6.  The  oil  shall  contain  not  more  than  eight  per  cent  (8%)  of  tar 
acids. 

7.  When  two  hundred  (200)  grams  of  the  oil  are  distilled  in  ac- 
cordance with  the  requirements  of  the  specifications  for  the  analysis 
of  coal-tar  dead  oil  or  coal-tar  creosote  hereinafter  referred  to  and 
results  calculated  to  water-free  oil: 

(a)  Not  more  than  five  per  cent  (5%)  of  oil  shall  distill  off  up  to 
two  hundred  and  five  degrees  Centigrade  (205°  C.). 

(b)  Not   more    than   thirty-five  per  cent    (35%)    of    oil   shall 
distill  off  up  to  two  hundred  and  thirty-five  degrees  Centigrade 
(235°  C.). 

(c)  Not  more  than  eighty  per  cent  (80%)  shall  distill  off  up  to 
three  hundred  and  fifteen  degrees  Centigrade  (315°  C.). 

(d)  The  coke  residue  shall  not  exceed  two  per  cent  (2%). 

(e)  The  distillate  between  two  hundred  and  five  (205)  degrees 
Centigrade  and  two  hundred  and  thirty-five  (235)  degrees  Centi- 
grade shall  deposit  naphthalene  on  cooling  to  fifteen  (15)  degrees 
Centigrade. 

NOTE. — The  percentage  distilling  to  two  hundred  and  forty-five  (245)  and  two 
hundred  and  seventy  (270)  degrees  Centigrade  shall  be  noted. 

[  623  ] 


Sec.  9  WOOD  PRESERVATION 

SECTION  2.— ANALYSIS  SPECIFICATIONS. 

GENERAL.  The  apparatus  employed  in  making  the  distillation 
and  other  tests  required  under  these  specifications  shall  conform  in 
general  to  that  shown  on  drawings  No.  1  (Fig.  356)  and  No.  2  (Fig. 
357)  attached  to  and  forming  a  part  of  these  specifications,  except 
that  a  five  per  cent  (5%)  variation  from  the  dimensions  given  is 
allowed.  The  distilling  apparatus  must  be  assembled  as  in  drawing 
No.  3  (Fig.  358).  As  further  defining  the  requirements  in  this  respect, 
the  following  description  of  certain  parts  and  manner  of  assembling  is 
given: 

(a)  Flask.    The  flask  required  is  a  Lunge  side  neck  distilling  flask, 
provided  with  a  trap  (drawing  No.  1)  (Fig.  356),  and  having  a  tubular 
thirty  centimeters  (30  cm.)  long  placed  close  to  the  bulb.     The  flask 
must  have  a  capacity  of  three  hundred  cubic  centimeters  (300  c.c.) 
when  filled  to  a  height  equal  to  its  maximum  horizontal  diameter. 

(b)  Thermometer.     The  thermometer  must  be  made  of  Jena  glass 
and  be  nitrogen  filled  and  graduated  at  intervals  of  one  millimeter 
(1  mm.)  in  single  degrees  Centigrade,  the  scale  reading  to  plus  four 
hundred  degrees  Centigrade  (+400°  C.). 

(c)  Receivers.  The  glass  receivers  may  be  of  any  convenient  size 
and  shape;  the  flask  shown  on  drawing  No.  2  (Fig.  357)  is,  however, 
recommended. 

(d)  Shield.  A  shield  ten  centimeters  (10  cm.)  in  diameter  and 
eight  centimeters  (8  cm.)  high,  made  of  asbestos  must  be  provided 
(drawing  No.  2)  (Fig.  357). 

(e)  Support  for  Flask.  The  flask  must  rest  on  an  asbestos  board 
one-half  centimeter  (.5  cm.)  in  thickness  by  fifteen  centimeters  (15 
cm.)  in  diameter,  a  hole  five  centimeters  (5  cm.)  in  diameter  being 
cut  in  the  center  of  the  board.    The  board  shall  rest  on  a  ring  stand 
(drawing  No.  2)  (Fig.  357). 

ASSEMBLING  APPARATUS.  The  apparatus  must  be  assembled  as 
shown  on  drawing  No.  3  (Fig.  358) .  The  thermometer  passes  through 
a  cork  in  the  top  of  the  flask  and  is  so  placed  that  the  top  of  the  bulb 
of  the  thermometer  is  on  a  line  with  the  bottom  of  the  tubular  outlet. 
The  asbestos  shield  is  placed  around  the  bulb  of  the  flask  and  the 
flask  mounted  on  the  asbestos  board  supported  on  the  ring  stand  as 
shown  on  drawing  No.  3  (Fig.  358). 

DISTILLATION  TEST.  Two  hundred  grams  of  the  oil  shall  be  used 
in  the  analysis,  this  amount  being  weighed  on  a  balance  sensitive 
to  one  milligram  (1  mg.),  in  the  following  manner: 

The  flask  is  first  placed  on  the  pan  of  the  balance  and  weighed, 
and  the  weight  recorded.  Without  removing  the  flask,  a  two 
hundred  (200)  gram  weight  is  placed  on  the  opposite  pan  of  the 
balance  and  a  sufficient  quantity  of  the  oil  dropped  into  the  flask 
through  a  long  stem  funnel  to  bring  the  pans  into  equilibrium. 
The  flask  is  then  removed  from  the  balance  and  set  up  as  in  drawing 
No.  3  (Fig.  358).  Care  must  be  taken  that  the  cork  stopper  carrying 
the  thermometer  fits  tightly  into  place.  The  flask  should  be  heated, 
preferably  by  a  Bunsen  or  other  standard  form  of  gas  burner.  The 

[624] 


WOOD  PRESERVATION 


Sec.  9 


D /STILLING  FLASK 


FIG.  356. — National  Electric  Light  Association  creosote  oil  analysis. 
[  625] 


Sec.  9 


WOOD  PRESERVATION 


r'^V  I 00  tern 


•fern 


FIQ.  357. — National  Electric  Light  Association  creosote  oil  analysis. 
[626] 


WOOD  PRESERVATION 


AiR /?A  NG£rt£N  T  OF 

D/STILL/NG  APPARATUS 


FIG.  358 — National  Electric  Light  Association  creosote  oil  analysis. 


[627] 


Sec.  9  WOOD  PRESERVATION 

distillation  shall  be  continuous  and  at  such  a  rate  that  two  (2)  drops 
of  oil  per  second  (5  c.c.  per  minute)  leaves  the  end  of  the  tubular  after 
the  thermometer  registers  two  hundred  and  five  degrees  Centigrade 
(205°  C.),  or  after  all  of  the  water  has  been  driven  off.  The  per- 
centage weights  of  the  following  fractions  shall  be  recorded : 

To  205  degrees  Centigrade. 
To  235  degrees  Centigrade. 
To  245  degrees  Centigrade. 
To  270  degrees  Centigrade. 
To  315  degrees  Centigrade. 
To  360  degrees  Centigrade. 


6.  "B"  SPECIFICATIONS  COVERING  MIXED  OILS  AND 
METHODS  OF  ANALYSIS. 

SECTION  1.— SPECIFICATION 

DEFINITION.  The  material  required  under  these  specifications 
is  a  homogeneous  mixture  of  a  distilled  product  obtained  from  coal 
gas  tar  or  coke  oven  tar  and  generally  known  as  coal-tar  dead  oil  or 
coal-tar  creosote  with  certain  other  hydrocarbons.  More  specifi- 
cally defined,  the  added  material,  which  must  constitute  not  more 
than  forty  (40)  per  cent  of  the  final  mixture,  may  consist  of : 

(a)  Raw  or  partly  distilled  coal-tar,  coke-oven  tar,  water-gas  tar, 
lignite  tar,  blast-furnace  tar,  and  producer  tar, 

or 

(b)  Distillates  from  any  of  the  above  mentioned  tars, 
or 

(c)  Products  obtained  by  filtration  of  any  of  the  above  mentioned 
tars. 

As  further  defining  the  material  required,  it  is  understood  that 
the  presence  in  the  oil  of  any  of  the  hydrocarbons  given  below  will, 
by  defeating  the  purpose  of  this  specification,  which  is  to  secure  a 
mixed  oil  containing  certain  hydrocarbons,  be  looked  upon  as  an 
adulteration  and  the  oil  may  be  rejected.  The  hydrocarbons 
provided  against  are  as  follows: 

(d)  Petroleum  oil  or  distillates  or  of  residues  therefrom. 

(e)  Water  gas  tar  containing  over  ten  per  cent  (10%)  paraffin  oil. 

(f)  Oil  tar  containing  over  ten  per  cent  (10%)  paraffin  oil. 

(g)  Distillates  or  residues  from  water  gas  tar  or  oil  tar  containing 
over  ten  per  cent  (10%)  paraffin  oil. 

CONDITIONS  OF  PURCHASE.  Same  as  in  specifications  covering 
coal-tar  creosote  oil. 

SAMPLING.  Same  as  in  specifications  covering  coal  tar  creosote 
oil. 

PHYSICAL  AND  CHEMICAL  CHARACTERISTICS.  The  oil  required 
under  these  specifications  must  have  the  following  characteristics : 

1.  It  shall  have  a  specific  gravity  of  at  least  one  and  four-hun- 

[623] 


WOOD  PRESERVATION  Sec.  9 

dredths  (1.04)  and  not  more  than  one  and  ten-hundredths  at  thirty- 
eight  degrees  Centigrade  (38°  C.). 

2.  There  shall  be  not  over  three  per  cent  (3%)  of  residue  insoluble 
in  hot  benzol. 

3.  The  oil  shall  contain  not  over  three  per  cent  (3%)  of  water. 

4.  The  residue  remaining  upon  sulphonating  a  portion  of  the 
total  distillate  shall  not  exceed  five  per  cent  (5%). 

5.  The  oil  shall  contain  not  less  than  two  per  cent  (2%)  nor  more 
than  eight  per  cent  (8%)  of  tar  acids. 

6.  When  two  hundred  (200)  grams  of  the  oil  are  distilled  in  ac- 
cordance with  the  requirements  of  the  specifications  for  the  analysis 
of  mixed  creosoting  oil  hereinafter  referred  to  and  results  calculated 
to  water  free  oil : 

(a)  Not  more  than  three  per  cent  (3%)  of  oil  shall  distil  off  up 
to  two  hundred  and  five  degrees  Centigrade  (205°  C.) 

(b)  Not  more  than  twenty-five  per  cent  (25%)  of  oil  shall 
distil  off  up  to  two  hundred  and  thirty-five  degrees  Centigrade 
(235°  C.). 

(c)  Not  more  than  eighty  per  cent  (80%)  shall  distil  off  to 
three  hundred  and  fifteen  degrees  Centigrade  (315°  C.).     . 

(d)  The  residue  above  three  hundred  and  sixty  degrees  Centi- 
grade (360°  C.)  shall  not  exceed  thirty-five  per  cent  (35%).* 

SECTION  2.— ANALYSIS  SPECIFICATION 
Same  as  in  Specifications  Covering  Coal-tar  Creosote  Oil 

7.  "C"    SPECIFICATIONS    COVERING    WATER-GAS   TAR 
CREOSOTE  OIL  AND  METHOD  OF  ANALYSIS. 

SECTION  1.— SPECIFICATION 

DEFINITION.  The  material  required  under  these  specifications 
is  that  known  as  dead  oil  of  water-gas  tar  or  water-gas  tar  creosote. 
More  specifically  defined,  it  is: 

(a)  A  distillate  from  the  tar  produced  as  a  by-product  in  the 
manufacture  of  carburetted  water  gas  from  petroleum  oil. 

It  is  understood  that  the  presence  of  any  other  hydro-carbons, 
either  in  the  original  tar  or  the  distillate  therefrom,  will,  by  defeating 
the  purpose  of  this  specification,  which  is  to  secure  a  pure  distilled 
oil  from  water-gas  tar,  be  looked  upon  as  an  adulteration,  which 
may  result  in  the  rejection  of  the  oil.  As  further  defining  the 
material  required,  the  hydrocarbons  specifically  provided  against, 
include: 

(b)  Raw  or  partly  distilled  tar  or  petroleum  oil  of  any  description, 
whatsoever,  such  as  coal  tar,  coke  oven  tar,  water  gas  tar,  oil  tar, 
lignite  tar,  wood  tar,  and  crude  petroleum. 

*NOTE. — The  percentage  distilling  to  two  hundred  and  forty-five  (245),  two 
hundred  and  seventy  (270)  and  three  hundred  and  sixty  (360)  degrees  Centigrade 
shall  be  noted. 

[629] 


Sec.  9  WOOD  PRESERVATION 

(c)  Distillates  from  any  of  the  above  mentioned  tars  or  oils, 
except  distillates  from  water  gas  tars. 

(d)  Residues  from  any  of  the  above  mentioned  tars  or  oils. 

(e)  Products  obtained  by  filtration  of  any  of  the  above  mentioned 
tars  or  oils. 

CONDITIONS  OF  PURCHASE.  Same  as  in  specifications  covering 
coal  tar  creosote  oil. 

SAMPLING.  Same  as  in  specifications  covering  coal  tar  creosote 
oil. 

PHYSICAL  AND  CHEMICAL  CHARACTERISTICS.  The  oil  required 
under  these  specifications  must  have  the  following  characteristics: 

1.  It  shall  have  a  specific  gravity  of  at  least  one  and  three-hun- 
dredths  (1.03)  and  not  more  than  one  and  eight-hundred ths  (1.08) 
at  thirty-eight  degrees  Centigrade  (38°  C.). 

2.  There  shall  be  not  over  one  per  cent  (1%)  of  residue  insoluble 
in  hot  benzol. 

3.  The  oil  shall  contain  not  over  two  per  cent  (2%)  of  water. 

4.  The  residue  remaining  upon  sulphonating  a  portion  of  the 
total  distillate  shall  not  exceed  five  per  cent  (5%). 

5.  When  two  hundred  (200)  grams  of  the  oil  are  distilled  in  ac- 
cordance with  the  requirements  of  the  specifications  for  the  analysis 
of  water  gas  tar  dead  oil  or  water-gas  tar  creosote  hereinafter  referred 
to  and  results  calculated  to  water  free  oil: 

(a)  Not  more  than  two  per  cent  (2%)  of  oil  shall  distil  off  up  to 
two  hundred  and  five  degrees  Centigrade  (205°  C.). 

(b)  Not  more  than  ten  per  cent  (10%)  of  oil  shall  distil  off  up 
to  two  hundred  and  thirty-five  degrees  Centigrade  (235°  C.). 

(c)  Not  more  than  sixty  p<*r  cent  (60%)  shall  distil  off  up  to 
three  hundred  and  fifteen  degrees  Centigrade  (315°  C.).* 

(d)  The  coke  residue  shall  not  exceed  two  per  cent  (2%). 

SECTION  2.— ANALYSIS  SPECIFICATIONS 

Same  as  in  Specifications  Covering  Coal  Tar  Creosote  Oil 

8.  AUXILIARY  SPECIFICATIONS. 

Methods  of  making  free  carbon  determination,  sulphonation  test, 
test  for  tar  acids,  and  test  for  coke,  as  referred  to  in  Specifications 
"A,"  "B"and  "C." 

DETERMINATION  OF  FREE  CARBON. 

The  apparatus  required  is  as  follows: 

Knorr  Condenser. 

Knorr  Flask. 

C.  S.  &  S.  No.  575  Filter  Papers,  15  cm.  diameter. 

Wire  for  supporting  filter  papers. 

Ten  grams  of  the  oil  should  be  weighed  into  a  small  beaker  and 
digested  with  C.  P.  toluol  on  a  steam  bath.  A  cylindrical  filter  cup 
is  prepared  by  folding  two  of  the  papers  around  a  rod  about  five- 

*  NOTE. — The  percentage  distilling  to  two  hundred  and  forty-five  (245)  and 
two  hundred  and  seventy  (270)  degrees  Centigrade  ehall  be  noted. 

L  630  J 


WOOD  PRESERVATION  Sec.  9 

eighths  of  an  inch  (f  *)  in  diameter.  The  inner  paper  should  be 
cut  to  fourteen  centimeters  (14  cm.)  diameter.  Prior  to  using  the 
filter  papers,  they  should  have  been  extracted  with  benzol  to  render 
them  fat  free.  The  filter  cup  is  dried  at  one  hundred  (100)  to  one 
hundred  and  ten  (110)  degrees  Centigrade  and  weighed  in  a  weighing 
bottle. 

The  contents  of  the  beaker  are  now  decanted  through  the  filter 
cup,  and  the  beaker  washed  with  hot  toluol,  passing  all  washings 
through  the  cup.  The  filtrate  should  be  passed  through  the  filter 
a  second  time,  the  residue  washed  two  or  three  times  with  hot  C.  P. 
benzol  and  transferred  to  the  extraction  apparatus,  in  which  C.  P. 
benzol  is  used  as  the  solvent,  which  solvent  is  vaporized  by  means 
of  a  steam  or  water  bath.  The  extraction  is  continued  until  the 
filtrate  is  colorless.  The  filter  cup  is  then  removed,  dried  and 
weighed  in  the  weighing  bottle.  C.  P.  benzol  followed  by  chloro- 
form may  be  used  instead  of  C.  P.  toluol  followed  by  C.  P.  benzol. 

Precautions.  In  removing  filter  paper  from  the  extraction  ap- 
paratus see  that  no  particles  of  mercury  find  their  way  into  the 
precipitate.  To  prevent  splashing,  the  filter  paper  should  be  ele- 
vated as  near  to  the  outlet  of  the  condenser  as  possible.  A  good 
precaution  is  to  cover  the  top  of  the  filter  cup  with  a  round  cap  of 
filter  paper. 

SULPHONATION  TEST.  Ten  cubic'centimeters  (10  c.c.)  of  the  total 
distillate  to  three  hundred  and  fifteen  degrees  Centigrade  (315°  C.) 
are  placed  in  a  flask  and  warmed  with  four  (4)  to  five  (5)  volumes 
of  concentrated  sulphuric  acid  to  sixty  degrees  Centigrade  (60°  C.) 
and  the  whole  transferred  to  a  graduated  separatory  funnel.  (The 
one  shown  on  drawing  No.  4  (Fig.  359)  is  recommended.  The  flask  is 
rinsed  three  times  with  small  quantities  of  concentrated  sulphuric 
acid  and  the  rinsings  added  to  the  contents  of  the  funnel,  which  is 
then  stoppered  and  shaken,  cautiously  at  first,  afterwards  vigorously, 
for  at  least  fifteen  (15)  minutes  and  allowed  to  Stand  over  night. 
The  acid  is  then  carefully  drawn  down  into  the  graduated  portion 
of  the  funnel  to  within  two  cubic  centimeters  (2  c.c.)  of  where  the 
unsulphonated  residue  shows.  If  no  unsulphonated  residue  is 
visible  the  acid  should  be  drawn  down  to  two  cubic  centimeters 
(2  c.c.).  In  either  case  the  test  should  be  carried  further  as  follows: 
Add  about  twenty  cubic  centimeters  (20  c.c.)  of  water  and  allow 
to  stand  for  one-half  hour.  Then  draw  off  the  water  as  close  as 
possible  without  drawing  off  any  supernatant  oil  or  emulsion,  add 
ten  cubic  centimeters  (10  c.c.)  of  strong  sulphuric  acid  and  allow  to 
stand  for  from  fifteen  to  twenty  (15-20)  minutes.  Any  unsulphon- 
ated residue  will  now  separate  out  clear  and  give  a  distinct  reading. 
If  under  two-tenths  of  a  cubic  centimeter  (.2  c.c.)  it  should  be  drawn 
down  into  the  narrow  part  of  the  funnel  to  just  above  the  stop-cock, 
where  it  can  be  estimated  to  one  one-hundredth  of  a  cubic  centi- 
meter (.01  c.c.) .  The  volume  of  residue  thus  obtained  is  calculated 
to  the  original  oil. 

DETERMINATION  OF  TAR  ACIDS.  One  hundred  cubic  centime- 
ters (100  c.c.)  of  the  total  distillate  to  three  hundred  and  fifteen 

[631] 


Sec.  9 


WOOD  PRESERVATION 


FIG.  359. — National  Electric  Light  Association  creosote  oil  analysis. 
[632] 


WOOD  PRESERVATION  Sec.  9 

degrees  (315°  C.),  to  which  forty  cubic  centimeters  (40  c.c.)  of  a 
solution  of  sodium  hydroxide  having  a  specific  gravity  of  one  and 
fifteen  hundredths  (1.15)  is  added,  is  warmed  slightly  and  placed  in 
a  separatory  funnel.  The  mixture  is  vigorously  shaken,  allowed 
to  stand  until  the  oil  and  soda  solutions  separate  and  the  soda 
solution  containing  most  of  the  tar  acids  drawn  off.  A  second  and 
third  extraction  is  then  made  in  the  same  manner,  using  thirty  (30) 
and  twenty  (20)  cubic  centimeters  of  the  soda  solution,  respectively. 
The  three  alkaline  extracts  are  united  in  a  two  hundred  cubic  centi- 
meter (200  c.c.)  graduated  cylinder  and  acidified  with  dilute  sul- 
phuric acid.  The  mixture  is  then  allowed  to  cool  and  the  volume  of 
tar  acids  noted.  The  results  shown  should  be  calculated  to  the 
original  oil. 

COKE  TEST.  In  making  the  coke  determination,  hard  glass 
bulbs  similar  to  the  one  shown  in  drawing  No.  4  (Fig.  359)  are  to  be 
used.  The  test  is  to  be  carried  out  as  follows: 

Warm  the  bulb  slightly  to  drive  off  all  moisture,  cool  in  a  desic- 
cator and  weigh.  Again  heat  the  bulb  by  placing  it  momentarily 
in  an  open  Bunsen  flame  and  place  the  tubular  underneath  the 
surface  of  the  oil  to  be  tested  and  allow  the  bulb  to  cool  until  suffi- 
cient oil  is  sucked  in  to  fill  the  bulb  about  two-thirds  full.  Any 
globules  of  oil  sticking  to  the  inside  of  the  tubular  should  be  drawn 
into  the  bulb  by  shaking  or  expelled  by  slightly  heating  it,  and  the 
outer  surface  should  be  carefully  wiped  off  and  the  bulb  re- weighed. 
This  procedure  will  give  about  one  gram  of  oil.  Cut  a  strip  of  thin 
asbestos  paper  about  one-quarter  inch  wide  and  about  one  inch  long, 
place  it  around  the  neck  of  the  bulb  and  catch  the  two  free  ends 
close  up  to  the  neck  with  a  pair  of  crucible  tongs.  The  oil  should 
then  be  distilled  off  as  in  making  an  ordinary  oil  distillation,  starting 
with  a  very  low  flame  and  conducting  the  distillation  as  fast  as  can 
be  maintained  without  spurting.  When  oil  ceases  to  come  over, 
the  heat  should  be  increased  until  the  highest  temperature  of  the 
Bunsen  flame  is  attained,  the  whole  bulb  being  heated  red  hot  until 
evolution  of  gas  ceases  and  any  carbon  sticking  to  the  outside  of  the 
tubular  is  completely  burned  off.  The  bulb  should  then  be  cooled 
in  a  desiccator  and  weighed  and  the  percentage  of  coke  residue  cal- 
culated to  water  free  oil. 

9.    SPECIFICATION   COVERING   OIL  FOR  BRUSH    TREAT- 
MENTS. 

The  material  required  under  these  specifications  is  the  same  as 
that  called  for  under  specification  "A,"  except  that  it  shall  have  a 
gravity  of  between  one  and  eight-hundredths  (1.08)  and  one  and 
twelve  hundredths  (1.12)  at  fifteen  degrees  Centigrade  (15°  C.). 
No  oil  to  distil  to  two  hundred  and  five  degrees  Centigrade  (205°  C.), 
and  not  more  than  ten  per  cent  (10%)  to  two  hundred  and  thirty- 
five  degrees  Centigrade  (235°  C.).  Not  more  than  one-half  of  one 
per  cent  (3/2%)  of  insoluble  matter  shall  be  left  upon  extraction  with 
hot  benzol. 

[  633  ] 


Sec.  9  WOOD  PRESERVATION 

TREATMENTS. 

10.  General.    The   following   recommended    methods   are   par- 
ticularly adaptable  for  the  local  treatment  of  line  timber  with  creo- 
sote.    They  include  standard  specifications  and  descriptions  of  the 
actual  working  plants  that  would  be  required  by  a  company  in  the 
event  of  the  treating  operation  being  carried  out  by  the  company's 
own  employees. 

The  following  methods  have  been  given  consideration: 

1.  Bethel  or  high-pressure  system 

2.  Open-tank  or  atmospheric  pressure  system 

3.  Brush  treatments 

11.  Pressure  System.     The  efficiency  of  the  straight  creosote, 
pressure  process,  cannot  be  questioned.     Still  it  should  be  under- 
stood, that  owing  to  the  heavy  cost  of  installing  such  a  system,  it 
would  come  within  the  province  of  comparatively  few  operating 
companies  to  own  an  outfit  of  this  kind.     At  the  same  time,  as  the 
number  of  creosoting  companies  increases,  a  considerable  quantity 
of  treated  line  timber  will  be  purchased,  and  it  is  for  the  purpose  of 
assisting  the  buyer  in  obtaining  the  best,  and  therefore  the  most 
economical  timber  for  the  money  expended,   that  the  following 
specifications  are  offered. 

12.  CREOSOTED  PINE  POLES. 

Creosoting.  Unless  otherwise  ordered,  all  poles  shall  be  impreg- 
nated with  not  less  than pounds  of ;•••-.•  creo- 
sote per  cubic  foot  of  wood,  in  accordance  with  the  specifications  for 
creosoting  timber.  The  creosote  used  in  impregnating  the  timber 
shall  conform  to  the  requirements  of  the  specifications  for  this  class 
of  material,  hereinafter  referred  to. 

Inspection.  The  quantity  of  creosote  forced  into  the  poles  shall 
be  determined  by  tank  measurements,  by  weighing  and  by  observing 
the  depth  of  penetration  of  the  oil  into  the  pole.  In  the  case  of  poles 
having  a  growth  of  sap  wood  not  less  than  one  and  one-half  (13^) 
inches  in  thickness,  the  depth  of  penetration  shall  not  be  less  than 
one  and  one-half  (1^)  inches.  In  the  case  of  poles  having  a  growth 
of  sap  wood  less  than  one  and  one-half  (13^)  inches  in  thickness  the 
creosote  shall  penetrate  through  the  sap  wood  and  into  the  heart  wood. 
The  depth  of  penetration  shall  be  determined  by  boring  the  pole 
with  a  one-inch  auger.  The  right  is  reserved  to  bore,  for  this  purpose, 
two  holes  at  random,  about  the  circumference,  one  hole  five  or  six 
(5  or  6)  feet  from  the  butt  and  one  hole  ten  (10)  feet  from  the  top. 
After  inspection,  each  bore  hole  shall  be  filled  with  hot  creosote  and 
then  with  a  close-fitting  creosoted  wooden  plug. 

The  inspector  may  satisfy  himself  that  no  portion  of  the  increased 
weight  is  due  to  the  presence  of  water,  which  may  have  condensed 
in  the  timber  in  consequence  of  the  steaming  process,  or  in  conse- 
quence of  the  presence  of  water  in  the  oil. 

Subsidiary  Specifications.  The  following  specifications  and 
drawing  form  a  part  of  these  specifications: 

[  634] 


WOOD  PRESERVATION  Sec.  9 

Specifications  for  creosoting  timber. 

Specifications  for  creosote. 

Drawing  No Framing  of  Poles. 

13.  CREOSOTING  OF  POLES.  These  specifications  cover  all 
directions  necessary  for  the  treatment  of  timber,  other  than  Douglas 
fir,  with  creosote.  These  specifications  do  not  cover  the  treatment 
of  cross-arms  and  are  not  to  be  used  in  connection  with  such  treat- 
ment. 

General.  These  specifications  describe  the  processes  to  be  used 
in  impregnating  timber,  except  cross-arms,  with  creosote  and  are 
intended  to  include  all  instructions  necessary  for  the  proper  per- 
formance of  the  work. 

Testing  Facilities.  The  manufacturer  shall  provide  and  install 
such  apparatus  as  is  necessary  to  enable  the  inspector  to  determine 
that  the  requirements  of  these  specifications  are  fulfilled.  It  is 
suggested  that  recording  temperature  and  pressure  instruments  be 
provided. 

Workmanship.  All  material  shall  be  of  the  best  quality  unless 
otherwise  specified  herein,  and  all  workmanship  shall  be  sound  and 
reliable  in  character  and  of  the  best  grade. 

Timber.  The  timber  subjected  to  the  creosoting  treatment  shall 
conform  to  the  requirements  of  the  specifications  and  drawings 
furnished  by  the  purchaser.  All  timber  shall  be  framed,  shaped  and 
bored  before  treatment.  The  material  in  each  charge  shall  be  in 
approximately  the  same  condition  so  far  as  air  seasoning  is  concerned, 
and  under  no  circumstances  shall  green,  partially  seasoned,  or 
seasoned  timber  be  treated  together  in  the  same  charge.  Species 
of  entirely  different  characteristics  shall  not  be  treated  together. 
When  the  southern  yellow  pines  are  treated,  long  leaf  and  Cuban 
pine  shall  not  be  included  in  charges  with  short  leaf  and  Loblolly 
pine. 

Creosote.  The  creosote  used  in  impregnating  the  timber  shall 
conform  to  the  requirements  of  the  purchaser's  specifications  for 
creosote.  The  purchaser  shall  have  the  right  to  take  samples  of 
the  oil  whenever  his  inspector  shall  elect.  The  sample  of  oil  so 
collected  shall  be  tested  wherever  the  purchaser  shall  elect.  When 
timber  is  being  treated,  the  oil  may  contain  not  more  than  five  (5) 
per  cent  of  water.  In  case  more  than  two  (2)  per  cent  of  water  is 
present  in  the  oil,  the  quantity  of  the  preservative  added  to  the 
timber  shall  be  increased  by  an  amount  sufficient  to  ensure  that  the 
required  amount  of  oil  computed  on  a  water-free  basis  has  been 
taken  up  by  the  timber. 

Quantity  of  Oil.  All  timber  shall  be  so  impregnated  with  creosote 
that  the  average  impregnation  of  the  material  in  each  cylinder  load 
shall  not  be  less  than  the  quantity  of  oil  called  for  in  the  specifications 
for  the  material  or  in  the  contract.  The  volume  of  timber  and  the 
quantity  of  oil  absorbed  shall  be  determined  by  the  inspector.  The 
inspector  shall  have  access  to  all  records  of  treatment.  Excess  of 
oil  in  one  charge  shall  not  be  offset  against  a  shortage  of  oil  in  another 

[  635  ] 


Sec.  9 


WOOD  PRESERVATION 


charge.  The  treating  plant  shall  be  equipped,  to  the  satisfaction 
of  the  purchaser,  so  as  to  allow  a  close  determination  of  the  amount 
of  oil  injected  into  the  timber.  The  quantity  of  oil  injected  into 
the  timber,  as  determined  by  the  volume  of  oil  withdrawn  from  the 
measuring  tanks,  shall  be  based  on  the  standard  temperature  of 
100°  F.  and  the  quantity  increased  by  an  amount  equal  to  0.00044  of 
the  required  volume  at  100°  F.  for  each  degree  of  Fahrenheit  of  oil 
temperature  above  the  standard  temperature  of  100°  F. 

General.  The  treating  cylinder  shall  not  be  opened  during  the 
process  of  treatment,  unless  under  instructions  of  inspector. 

Classification.  For  the  treating  process  timber  shall  be  classified 
as  heavy  or  small.  Heavy  timber  shall  be  understood  to  include 
poles  and  stubs;  small  timber  shall,  unless  otherwise  specified, 
include  all  other  timber-,  except  cross-arms,  ordered  by  the  purchaser. 

Steaming  and  Heating  Process.  Steam  when  used  shall  be 
maintained  at  a  uniform  pressure  and  temperature  in  the  treating 
cylinder  as  indicated  in  the  following  table: 


For  heavy  timber  .... 
For  small  timber  .... 

Steam  Pressure 
Not  less  than 

Steam  Pressure 
Not  greater 
than 

Steam  Temper- 
ature Not 
greater  than 

17  pounds 
12  pounds 

20  pounds 
15  pounds 

259  F. 
250  F. 

The  temperature  reading  shall  be  taken  by  means  of  standard 
thermometers  placed  in  the  treating  cylinder  so  that  the  bulbs 
thereof  are  within  the  shell.  At  the  beginning  of  the  steaming 
process  the  exhaust  valve  shall  be  open  and  shall  not  be  closed 
until  a  steady  flow  of  steam  escapes  through  the  valve.  The 
duration  of  the  steaming  process  shall  be  timed  from  the  closing  of 
the  exhaust  valve.  The  exhaust  valve  shall  be  opened  and  the 
condensation  blown  off  at  intervals  during  the  steaming  process. 
The  duration  of  the  steaming  process  shall  be  as  directed  by  the 
inspector  and  shall  depend  upon  the  condition  and  character  of 
the  timber,  but  shall  in  no  case  be  carried  to  such  an  extent  as  to 
injure  the  timber.  The  timber  shall  not  be  steamed  in  excess  of 
the  interval  given  in  the  following  table: 


For  heavy  timber  
For  small  timber  

Green  or  Very 
Wet  Timber 

Partially 
Seasoned  Timber 

Seasoned 
Timber 

8  hours 
5  hours 

5  hours 
S  hours 

0  hours 
0  hours 

Seasoned  timber  shall  not  be  steamed,  but  shall  be  heated  in 
the  treating  cylinder.     The  temperature  within  the  cylinder  shall 

[636] 


WOOD  "PRESERVATION  Sec.  9 

be  maintained  by  means  of  the  closed  heating  coils  at  a  temperature 
of  about  150°  F. 

For  heavy  timber for  at  least  2  hours 

For  small  timber '  "    1  hour 

Exhaustion   Process    Green    and    Partially    Seasoned    Timber. 

When  the  steaming  process  shall  have  been  completed  the  steam 
shall  be  blown  off  and  the  treating  cylinder  exhausted  to  a  vacuum 
of  at  least  twenty-four  (24)  inches  at  or  near  sea  level,  or  propor- 
tionately less  at  higher  altitudes.  The  vacuum  shall  be  maintained 
at  the  above  minimum  for  a  period. 

For  heavy  timber of  not  less  than  2  hours 

For  small  timber '  "1  hour 

and  if  necessary  thereafter  until  the  condenser  discharge  is  clear. 
During  the  exhaustion  process  the  temperature  within  the  treating 
cylinder  shall  be  maintained,  by  means  of  saturated  steam  in  the 
closed  heating  coils,  above  that  at  which  water  would  boil  at  that 
degree  of  vacuum. 

Exhaustion  Process  Seasoned  Timber.  With  seasoned  timber 
•it  is  not  required  that  a  vacuum  shall  be  drawn  after  the  heating 
process  and  before  the  filling  process,  provided  that  the  specified 
amount  of  creosote  is  in  the  timber  on  its  removal  from  the  treating 
cylinder. 

Filling  Process.  After  the  exhaustion  process,  the  cylinder  shall 
be  completely  filled,  as  rapidly  as  possible,  with  creosote  and  in  no 
case  shall  the  flow  of  oil  into  the  treating  cylinder  be  stopped  before 
the  overflow  of  the  cylinder.  Pressure  shall  then  be  applied  until 
the  specified  amount  of  oil  has  been  forced  into  the  timber.  The 
total  amount  of  oil  forced  into  the  timber  shall  be  determined  from 
the  initial  reading  on  the  measuring  tanks,  and  from  the  readings 
on  the  measuring  tanks,  after  the  oil  in  the  cylinder  at  the  con- 
clusion of  the  pressure  process  (including  all  drip  from  the  timber), 
has  been  returned  to  the  measuring  tanks. 

The  oil  at  introduction  into  the  cylinder  shall  have  a  temperature 
of  not  less  than  140  degrees  Fahrenheit  and  not  more  than  175 
degrees  Fahrenheit.  The  oil  in  the  measuring  tanks  shall  be  main- 
tained at  a  uniform  temperature  during  the  filling  process. 

Subsidiary  Specifications.  The  following  specifications  of  the 
purchaser  form  a  part  of  these  specifications: 

Specification  for creosote. 

Specification  for  analysis  of creosote. 

14.  CREOSOTED  PINE  CROSS-ARMS.     (Sec.  4,  Art.  4.) 

Inspection.  Inspection,  unless  otherwise  arranged,  shall  be  at 
the  creosoting  plant  before  and  after  treatment.  All  cross-arms 
shall  be  inspected  for  dimensions  and  defects  outlined  under  "quality"' 
before  being  subjected  to  the  creosoting  process.  The  quantity  of 
creosote  forced  into  the  arms  shall  be  determined  by  tank  measure- 
ments and  by  noting  the  depth  of  penetration  of  the  oil  and  by 

[  637  ] 


Sec.  9  WOOD  PRESERVATION 

weighing.  The  right  is  reserved  to  select,  at  random,  one  arm  in 
each  hundred  to  be  sawed  for  the  purpose  of  determining  the  pene- 
tration. All  cross-arms  not  conforming  to  all  requirements  of  this 
specification  shall  be  rejected. 

Sapwood  Classification.  No  limitation  is  placed  on  the  amount  of 
sap  wood  which  may  be  contained  in  any  arm.  All  cross-arms  con- 
taining both  sapwood  and  heartwood  shall,  however,  be  shaped  so 
that  the  sapwood  shall  be  on  the  top  or  sides  of  the  cross-arm.  All 
crossarms  shall  be  divided,  before  treatment,  with  respect  to  the 
amount  of  sapwood  contained  by  each  into  three  classes  as  follows: 

Class  "  H"  not  more  than  twenty-five  (25)  per  cent  of  sapwood. 
Class  'S"  not  less  than  seventy-five  (75)  per  cent  of  sapwood. 
Class  "I"  not  included  in  classes  "H"  and  "S." 

Treatment.  Each  class  of  cross-arms  shall  then  be  separately 
treated  in  accordance  with  the  requirements  of  the  "Specification 
for  Creosoting  Yellow  Pine  Cross-arms"  hereinafter  referred  to,  with 
the  amounts  of creosote  shown  in  the  following  table : 

Class  "H"  cross-arms  not  less  than  eight  (8)  pounds  per  cubic  foot  ot 

timber. 
Class  "S"  cross-arms  not  less  than  twelve  (12)  pounds  per  cubic  foot  of 

timber. 
Class  "  I "  cross-arms  not  less  than  ten  (10)  pounds  per  cubic  foot  of  timber . 

The    creosote  used  in  treating  the  cross-arms  shall 

conform  to  the  requirements  of  the  specifications  for  this  class  of 
material,  hereinafter  referred  to. 

Subsidiary  Drawings  and  Specifications.  The  following  drawing 
and  specifications  form  a  part  of  these  specifications. 

Drawing     No standard    cross-arm. 

Specification  for  creosoting  pine  cross-arms. 

Specification  for  Creosote. 

15.  CREOSOTING  OF  PINE  CROSS-ARMS. 

General.  This  specification  describes  the  process  to  be  used  in 
impregnating  yellow  pine  cross-arms  with  creosote  and  is  intended  to 
include  instructions  necessary  for  the  proper  performance  of  the 
work. 

Testing  Facilities.  The  manufacturer  shall  provide  and  install 
such  apparatus  as  is  necessary  to  enable  the  inspector  to  determine 
that  the  requirements  of  these  specifications  are  fulfilled.  It  is 
suggested  that  recording  temperature  and  pressure  instruments  be 
provided. 

Workmanship.  All  workmanship  shall  be  sound  and  reliable  in 
character  and  of  the  best  commercial  grade. 

Cro  ss-arms.  The  cross-arms  sub j  ected  to  the  creosoting  treatment 
shall  conform  to  the  requirements  of  the  specifications  and  drawings 
furnished.  All  cross-arms  shall  be  shaped,  bored  and  well  seasoned 
before  treatment. 

Creosote.  The  creosote  used  in  impregnating  the  cross-arms  shall 
conform  to  the  requirements  of  the  specifications  for  creosote  here- 

[  638  ] 


WOOD  PRESERVATION  Sec.  9 

inafter  referred  to.  The  right  is  reserved  to  take  samples  of  the 
oil  at  any  stage  of  the  creosoting  process  and  to  test  the  samples 
wherever  desired. 

Water  In  Oil.  The  inspector  shall  frequently  take  a  sample  of 
oil  from  the  treating  cylinder  and  distill  it  to  two  hundred  and  five 
(205)  degrees  Centigrade,  in  order  to  determine  the  percentage  of 
water  present.  If  the  amount  of  water  is  in  excess  of  five  (5)  per 
cent,  the  treatment  shall  be  discontinued  until  the  excess  water  has 
been  removed  from  the  oil  or  until  oil  containing  not  more  than 
the  allowable  amount  of  water  can  be  supplied.  In  case  more  than 
two  (2)  per  cent  of  water  is  present  in  the  oil,  the  quantity  of  the 
•preservative  added  to  the  timber  shall  be  increased  by  an  amount 
sufficient  to  insure  that  the  required  amount  of  oil,  computed  on 
water-free  basis,  has  been  taken  up  by  the  timber. 

Quantity  of  Oil.  All  crossarms  shall  be  so  impregnated  with 
creosote  that  the  average  impregnation  of  the  material  in  each 
cylinder  load  shall  not  be  less  than  the  quantity  of  oil  hereinafter 
specified.  The  volume  of  timber  and  the  quantity  of  oil  absorbed 
shall  be  determined  by  the  inspector.  The  inspector  shall  have 
access  to  all  records  of  treatment. 

Excess  of  oil  in  one  charge  shall  not  be  offset  against  a  shortage 
of  oil  in  another  charge 

The  treating  plant  shall  be  equipped  so  as  to  allow  a  close 
determination  of  the  amoHnt  of  oil  injected  into  the  timber. 

The  quantity  of  oil  injected  into  the  cross-arms  as  determined 
by  the  volume  of  oil  withdrawn  from  the  measuring  and  working 
tanks,  shall  be  based  on  the  standard  temperature  of  one  hundred 
(100)  degrees  Fahrenheit.  The  correction  to  be  applied  in  com- 
puting the  quantity  ot  the  injected  oil  shall  consist  in  the  addition 
of  .00044  of  the  required  volume  for  each  degree  Fahrenheit  the 
temperature  of  the  measured  oil  exceeds  the  standard  temperature 
of  100  degrees  Fahrenheit. 

Treatment. — Gential.  The  treating  cylinder  shall  not  be  opened 
during  treatment,  unless  so  ordered  by  the  Inspector. 

Classification.  For  the  treating  process  all  cross-arms  shall  be 
divided,  with  respect  to  the  amount  or  sapwood  contained  by  each 
into  three  classes  as  follows : 

Class  H  not  more  than  25  per  cent  of  sapwood. 
Class  S  not  less  than  75  per  cent  of  sapwood. 
Class  I  between  classes  H  and  S. 

Each  class  of  cross-arms  shall  be  carried  through  the  entire  treat- 
ing process  separately.  In  no  case  shall  a  given  cylinder  load  con- 
tain more  than  one  class  of  cross-arms,  nor  shall  it  contain  cross-arms 
of  different  sizes. 

Heating  Process.  The  seasoned  and  inspected  cross-arms  shall 
be  placed  in  the  treating  cylinder,  the  temperature  within  which 
shall  be  maintained  by  means  of  the  closed  heating  coils  at  a  tem- 
perature of  about  one  hundred  and  fifty  (150)  degrees  Fahrenheit 
tor  at  least  one  (1)  hour. 

[  639] 


Sec.  9  WOOD  PRESERVATION 

Exhaustion  Process.  It  is  not  required  that  a  vacuum  shall  be 
drawn  after  the  heating  process  and  before  the  filling  process,  pro- 
vided the  specified  amount  of  creosote  can  be  injected  into  the  timber 
without  the  previous  application  of  a  vacuum. 

Filling  Process.  After  the  heating  process  or  after  the  exhaustion 
process  in  cases  where  the  latter  is  applied,  the  cylinder  shall  be 
completely  filled,  as  rapidly  as  possible,  with  creosote,  and  in  no 
case  shall  the  flow  of  oil  into  the  treating  cylinder  be  stopped  before 
the  overflow  of  the  cylinder.  This  shall  be  determined  by  means  of 
an  overflow  valve  at  the  top  of  the  cylinder.  All  air  must  be 
removed  from  the  cylinder  before  pressure  is  applied.  Pressure 
shall  then  be  applied  until  the  amount  of  oil  required  for  each  class 
of  cross-arms  has  been  forced  into  the  timber.  Each  class  of  cross- 
arms  shall  be  impregnated  with  the  amounts  of  creosote  shown  in 
the  following  table: 

Class  H  cross-arms  not  less  than  8  pounds  per  cubic  foot  of  timber. 
Class  S  cross-arms  not  less  than  12  pounds  per  cubic  foot  of  timber. 
Class  I  cross-arms  not  less  than  10  pounds  per  cubic  foot  of  timber. 

The  total  amount  of  oil  forced  into  the  cross-arms  shall  be 
determined  from  the  initial  reading  on  the  measuring  and  working 
tanks,  and  the  reading  on  the  measuring  and  working  tanks  after 
the  oil  in  the  cylinder  at  the  conclusion  of  the  pressure  process, 
including  all  drip  from  the  cross-arms,  after  it  has  been  returned 
to  the  measuring  tanks. 

The  oil  at  introduction  into  the  cylinder  shall  have  a  temperature 
of  not  less  than  one  hundred  and  forty  (140)  degrees  Fahrenheit 
and  not  more  than  one  hundred  and  seventy-five  (175)  degrees 
Fahrenheit  maintained  at  the  initial  temperature  during  the  whole 
process  of  forcing  the  oil  into  the  cross-arms. 

Subsidiary  Specifications.  The  following  specifications  form  a 
part  of  this  specification: 

Specification creosote. 

Specification  for  analysis  of creosote. 

16.  OPEN  TANK  SYSTEM.     The  efficacy  of  treating  the  butts 
of  poles  by  the  open  tank  method  is  now  fairly  well  recognized.     It 
appeals  at  once  to  the  operating  man  on  account  of  its  simplicity, 
and  as  the  application  of  the  oil  is  made  at  the  butts  of  the  poles 
where  they  are  most  susceptible  to  deterioration,  the  method  is 
economical.     Moreover,  the  process  may  be  satisfactorily  carried 
out  by  and  under  the  control  of  the  consumer.     General  directions 
are  given  in  the  following  as  a  guide  for  carrying  out  the  open-tank 
method  of  treating  poles  and  crossarms. 

17.  OPEN  TANK  TREATMENT  OF  POLE  BUTTS.    All  the 
inner  bark  should  be  thoroughly  shaved  from  the  poles  in  order  that 
the  best  penetration  by  the  oil  may  be  secured.  After  cutting,  the  poles 
should  be  piled  and  stored  in  layers  at  least  twelve  inches  above  the 
ground  with  sufficient  space  between  each  pole  and  each  layer  to 

[640] 


WOOD  PRESERVATION  Sec.  9 

allow  for  circulation  of  air,  also  to  prevent  the  accumulation  of  snow 
and  moisture,  and  to  facilitate  thorough  seasoning.  All  poles  should 
be  at  least  air  dried  and  have  not  less  than  three  months'  seasoning 
before  treatment.  Poles  of  different  classifications  or  different 
species  of  wood  should  not  be  treated  in  the  same  charge. 

Hot  Bath.  In  the  hot  bath,  the  poles  should  be  kept  in  oil  main- 
tained at  a  temperature  of  200  to  220  degrees  Fahrenheit,  for  from 
one  to  three  hours. 

Cold  Bath.  At  the  completion  of  the  hot  oil  treatment,  the  poles 
should  be  placed  in  the  cold  oil,  or  the  hot  oil  changed  to  cold  oil, 
(oil  at  the  temperature  of  surrounding  atmosphere)  for  from  one  to 
three  hours. 

Time  of  Treatment.  No  attempt  is  made  to  specify  the  exact 
time  of  either  the  hot  or  cold  treatment,  because  this  can  best  be 
determined  by  trial.  It  is  understood  that  a  complete  penetration 
of  the  sap  wood  should  be  secured. 

Control.  It  should  also  be  explained  that  where  the  apparatus 
is  not  equipped  for  both  hot  and  cold  baths,  it  will  be  necessary  to 
permit  the  hot  bath  to  cool  down  to  the  temperature  of  the  atmos- 
phere. 

Penetration.  Poles  should  be  examined  for  depth  of  penetration 
of  oil  by  boring  samples  at  about  four  feet  from  the  butt  end.  The 
bored  holes  should  be  filled  with  hot  creosote  oil  immediately  after 
the  depth  of  penetration  has  been  ascertained.  The  quantity  of 
creosote  oil  injected  should  be  determined  by  tank  measurements. 
All  tops  and  gains  of  poles  should  be  brush-treated  with  two  coats 
of  hot  oil.  (See  Article  on  Preservatives  for  specification  for  oil 
for  brush  treatments.) 

Treatment.  The  cross-arms  should  be  treated  by  immersing 
them  for  at  least  thirty  minutes  in  hot  oil  at  from  200  to  220  degrees 
Fahrenheit,  and  then  leaving  them  in  cold  oil  for  one  hour,  or  more. 
The  necessary  duration  of  each  bath  is  best  determined  by  trial. 
If  complete  penetration  of  sap  wood  is  not  obtained,  the  length  of 
time  should  be  proportionately  increased. 

Specifications  •have  not  been  provided  for  a  special  oil  for  open 
tank  treatments.  It  is  true  that  perhaps  excessive  evaporation  will 
result  by  using  the  ordinary  oil,  but  the  loss  sustained  is  likely  to 
be  less  than  the  extra  cost  of  an  especially  prepared  oil. 

18.  DESCRIPTION  OF  OPEN-TANK  PLANTS.  To  meet  the 
different  local  conditions  existing  among  the  member  companies, 
four  open-tank  plants  have  been  designed  and  the  working  plans 
referred  to  show  the  details  of  their  construction: 

1.  Open-tank  plant  designated  aa  "Type  A." 

2.  Open-tank  plant  designated  as  "Type  B." 

3.  Open-tank  plant  designated  as  "Type  C." 

4.  Open-tank  plant  designated  as  "Type  D." 

Types  "A,"  "B"  and  "C"  are  intended  for  the  treatment  of 
pole  butts,  while  Type  "D"  is  for  the  treatment  of  cross-arms. 

It  has  been  impossible  to  include  the  valuable  detail  drawings  of 
21  [  641  ] 


Sec.  9  WOOD  PRESERVATION 

the  different  types  of  open-tank  plants  included  In  the  1911  report, 
owing  to  the  fact  that  they  could  not  be  reproduced  to  a  sufficiently 
large  scale  to  be  intelligible.  For  exact  detail  information,  it  will 
be  necessary  to  consult  the  report  as  printed  in  full  in  the  1911  Pro- 
ceedings of  the  National  Electric  Light  Association.  The  original 
report  should  also  be  consulted  for  costs  of  the  different  types  of 
open-tank  plants;  also  for  drawing  and  details  of  a  portable  tank 
for  brush  treatments. 

Open-Tank  Plant  Type  "A."  This  plant  has  a  capacity  of  fifty 
poles  per  charge,  and  at  least  one  hundred  poles  per  day. 

A  plant  of  such  ample  size  is  recommended  for  the  use  of  the  larger 
companies  who  may  find  it  advisable  to  construct  a  permanent 

?lant  and  who  use  sufficient  poles  to  warrant  such  an  investment, 
b  will  be  seen  from  the  plan  that  a  steam  siding  is  included  and  a 
power-driven  derrick,  so  that  heavy  manual  labor  will  be  reduced 
as  much  as  possible.  Liberal  yard  room  is  also  provided  at  one 
side  of  the  plant  for  the  piling  and  seasoning  of  the  untreated  poles, 
and  at  the  other  for  storing  the  treated  poles. 

The  general  layout  of  piping  and  tanks  is  so  designed  that  this 
arrangement  affords  a  plant  which  is  easily  controlled  and  operated. 
The  oil  bath  in  the  treating  tanks  may  be  quickly  changed  from  hot 
to  cold.  The  storage  tanks  are  elevated  sufficiently  above  the 
treating  tanks  so  that  the  oil  will  flow  by  gravity  into  the  treating 
tanks.  A  plunger  pump,  having  a  capacity  of  200  gallons  per  minute, 
is  connected  so  that  it  discharges  either  from  the  receiving  tank 
directly  into  the  treating  tanks,  or  into  the  storage  tanks.  A  turbine 
drive,  three-inch  centrifugal  pump  may  be  substituted  for  the 
plunger  pump,  and  the  receiving  tank  eliminated,  if  found  advisable. 
The  piping  shown  is  of  liberal  size,  so  that  the  time  of  changing  the 
hot  and  cold  oil  will  be  reduced  to  a  minimum.  Steam  coils  are 
provided  in  the  storage,  receiving  and  treating  tanks,  and  the  area 
of  the  treating  tank  is  sufficient,  figuring  two  square  feet  of  surface 
per  pole,  to  accommodate  25  poles.  Each  storage  tank  is  10  feet 
in  diameter,  and  20  feet  high,  giving  a  capacity  of  about  11,500 
gallons  so  that  oil  may  be  purchased  in  tank-car  lots.  The  treating 
tanks  contain  sufficient  heating  coils  to  raise  the  temperature  of  the 
oil  from  zero  to  two  hundred  and  twenty  (220)  degrees  Fahrenheit. 
The  coils  are  separated  by  6-inch  "I"  beams,  which  have  riveted 
on  the  top  flanges  3^-inch  by  2^-inch  by  5/16-inch  angle  irons  to 
support  the  poles.  Angle  irons  are  used  instead  of  flat  bars  so  that 
when  the  end  of  a  pole  is  once  placed  on  the  bottom  of  the  tank  it 
will  not  change  its  position.  The  derrick  intended  for  the  outfit 
consists  of  an  8-inch  by  10-inch  boom,  4  feet  long,  two  8-inch  by 
8-inch  stiff  legs,  each  40  feet  long,  one  8-inch  by  8-inch  mast,  30 
feet  long,  and  two  sills  8  inches  by  8  inches,  30  feet  long,  complete 
with  derrick  irons;  one  10-foot  diameter  bull  wheel  with  guide 
sheaves  framed  up  complete,  together  with  wire  rope  and  clips  to 
connect  the  bull  wheel  with  the  swinging  gear.  The  derrick  is 
equipped  with  ^-inch,  cast  steel  cable,  (hemp  center)  and  with 
steel  blocks  having  self  lubricating  bronze  bushings.  The  engine 

[642] 


WOOD  PRESERVATION  Sec.  9 

operating  the  derrick  is  a  double  6%-mch  by  8-inch  cylinder,  tandem, 
friction  drum  hoist  engine;  drums  being  14-inch  diameter,  16-inch 
face  equipped  with  ratchet  pauls  and  foot  brakes.  The  boiler  is  of 
the  vertical  locomotive  type,  50  horse-power  capacity. 

It  should  be  understood  that  the  equipment  may  be  modified  to 
meet  special  requirements  and  a  further  description  will  not  be  dwelt 
upon,  as  local  conditions  governing  each  installation  will  have  to  be 
given  due  consideration.  For  example,  in  very  moist  ground,  it 
would  probably  be  advisable  to  build  the  plant  high,  rather  than  to 
excavate  deep,  and  again,  the  capacity  of  the  plant  may  be  increased 
or  diminished  by  changing  the  diameter  of  the  treating  cylinders, 
and  by  substituting  a  turbine  driven  centrifugal  pump.  Likewise 
a  cheap  derrick  could  be  used  with  a  steel  cable  runner,  from  a  drum 
and  engine  located  in  the  boiler  house. 

Open-Tank  Plant  Type  "B"  has  a  maximum  capacity  of  28 
poles  per  day.  This  outfit  is  intended  for  a  temporary  pole 
treating  plant  for  a  large  company,  or  as  a  permanent  outfit 
for  small  concerns.  A  fairly  good  control  of  the  oil  is  secured 
by  the  use  of  a  centrifugal  pump.  The  hot  oil  may  be  quickly 
pumped  into  the  top  of  the  storage  tank  and  at  the  same  time  the 
cold  oil  is  filling  the  treating  tank.  Hot  and  cold  regulation  of  oil 
may  also  be  accomplished  without  uncovering  the  poles.  The  tanks 
are  heated  with  steam  from  a  small  locomotive  type,  20  horse-power, 
vertical  boiler,  and  if  found  desirable,  the  derrick  may  be  operated 
by  steam.  The  design,  however,  shows  it  operated  by  a  hand  winch. 
The  plant  has  one  11,500  gallon  capacity,  storage  tank.  This  is 
provided  so  that  oil  may  be  purchased  in  carload  lots,  thereby  giving 
the  consumer  the  benefit  of  the  lowest  price  for  the  preservative. 
The  scheme  is  flexible;  there  is  no  permanent  foundation,  and  the 
plant  may  be  moved  from  place  to  place. 

Possible  modifications  of  the  type  "B"  open-tank  outfit  are 
apparent,  as  in  the  case  ot  type  "A."  The  treating  tank  shown 
is  6  feet  in  diameter.  This  could  be  increased  to  a  diameter  that 
would  allow  a  proportionately  greater  number  of  poles  per  charge, 
thereby  increasing  the  ultimate  capacity.  In  the  capacity  figured 
above,  (about  24  poles  per  day)  it  was  estimated  that  the  treating 
tank  would  be  charged  twice  and  a  cycle  of  operation  would  be  six 
hours.  It  would  probably  be  possible  to  crowd  the  capacity  to  at 
least  36  poles  per  day.  With  either  the  type  "A"  or  type  "B" 
plants  the  special  boiler  equipment  could  be  eliminated,  if  they  were 
located  adjacent  to  a  permanent  steam  plant. 

Open-Tank  Plant  Type  "C"  has  a  capacity  of  twelve  poles  per  day. 

Type  "C"  plant  may  be  used  where  the  number  of  poles  to  be 
treated  is  small  and  the  pole  treating  is  to  be  carried  on  in  an  isolated 
place.  This  plant  is  quite  elementary.  It  is  apparent  that  the 
regulation  is  poor,  it  being  necessary  to  heat  the  oil  to,  say,  200 
degrees  Fahrenheit,  retaining  the  temperature  at  or  near  that  point 
for  three  hours,  and  then  after  drawing  the  fire,  permit  the  oil  to 
cool  down  to  atmosphere.  This  operation  gives  a  heavy  treatment, 
with  practically  no  control.  The  same  outfit  may  be  arranged 

[  643  ] 


Sec.  9 


WOOD  PRESERVATION 


without,  the  fire  box,  having  heating  coils  in  the  bottom  of  the  tank, 
the  coils  being  connected  to  an  independent  boiler  or  to  a  steam 
supply  from  an  adjacent  plant.  Such  a  modification  would  give 
control  of  the  hot  treatment,  but  not  of  the  cold. 

Open-Tank  Plant  Type  "D"  is  designed  for  the  treatment  of 
cross-arms,  the  capacity  is  approximately  300  cross-arms  per  day. 


The  cross-arm  plant  consists  of-two^steel  tanks,  one  for  the  hot 
and  one  for  the  cold  oil,  each  12  feet  long,  3  feet  wide  and  2  feet  high, 
arranged  side  by  side.  The  hot  oil  tank  is  equipped  with  four  pairs 
of  1^-inch  steam  coils,  connected  to  a  separate  boiler,  or  to  adjacent 

[644] 


WOOD  PRESERVATION 


Sec.  9 


FIG.  361 
[645] 


Sec.  9 


WOOD  PRESERVATION 


WOOD  PRESERVATION 


nj&SiiKVATION  o 


[647] 


Sec.  9 


WOOD  PRESERVATION 


tests  show  sufficient  penetration,  the  cross-arms  should  be  taken  out 
and  piled  on  the  drip  table  to  dry. 

Figure  360  is  from  a  photograph  of  an  open-tank  pole  treating 


FIG.  364. — These  timbers  were  supposed  to  have  had  the  same  treatment. 

Notice  erratic  results  obtained,  due  to  adhering  bark 

and  unequal  seasoning. 

plant,  in  which  the  cost  of  handling  the  poles  is  reduced  to  a  mini- 
mum, but  this  plant  has  but  small  capacity,  and  control  of  the  cold 
bath  is  not  obtained.  Figures  361  and  362  show  open-tank  pole 

[  648  ] 


WOOD  PRESERVATION 


Sec.  9 


treating  plants  that  fairly  well  represent  types  "B"  and  "C."  A 
false  bottom  for  holding  poles  in  position  in  bottom  of  treating  tank 
is  illustrated  in  Figure  363. 

Wide  variation  in  oil  penetration  resulting  from  unequal  seasoning 


is  illustrated  in  Figure  364.  This  shows  timber  supposed  to  have  had 
the  same  treatment.  Figure  365  shows  a  green  and  a  seasoned  pole 
of  the  same  species,  both  treated  by  the  open-tank  method.  The 
effect  of  seasoning  on  the  efficiency  of  the  treatment  is  very  marked. 

[649] 


Sec.  9  WOOD  PRESERVATION 

19.  BRUSH  TREATMENT.  Much  of  the  line  timber  treated  at 
present  is  by  the  brush  method.  Although  this  treatment  is  less 
efficient  than  the  pressure  or  open-tank  system,  it  is  recognized  as 
often  desirable  and  is  used  by  many  in  the  absence  of  more 
thorough  methods.  Unless  absolutely  unavoidable,  the  timber  should 
not  be  treated  when  it  is  green,  wet  or  frozen.  It  should  be  borne 
in  mind  that  by  not  properly  carrying  out  the  brush  treatment  it  is 
an  easy  matter  to  render  the  treatment  worthless. 

Coal  tar,  creosote  oil  (see  specifications  for  oil  for  brush  treatments, 
Articles  on  Preservatives)  should  be  applied  with  a  three  or  four  knot 
rubberset  or  wire  bound  roofing  brush,  the  oil  having  been  heated 
to  a  temperature  of  200  degrees  Fahrenheit.  All  crevices  and  shakes 
should  be  filled  with  the  oil,  using  the  same  liberally  for  the  first  coat. 
The  second  coat  should  not  be  applied  until  the  preceding  coat  has 
been  fully  absorbed.  It  is  best  to  apply  the  different  coats  on 
different  days.  Tops  and  gains  of  poles  should  also  receive  two 
brush  coats  of  the  preservative. 

A  spraying  machine  may  be  used  for  the  application  of  the  oil  to 
the  butts  of  poles.  It  has  the  advantage  of  filling  up  the  cracks 
and  season  checks,  and  probably  with  this  method  the  poles  do  not 
have  to  be  handled  so  much  as  when  the  brush  is  used.  However, 
the  advantage  of  low  cost  of  application  is  probably  lost  on  account 
of  the  oil  wasted  in  spraying  the  poles. 


[650] 


SECTION  9 

PRESERVATIVE  TREATMENT  OF  POLES 
•    AND  CROSS-ARMS 


PART  III 
APPENDICES 


SECTION  9 

PRESERVATIVE  TREATMENT  OF  POLES 
AND  CROSS-ARMS 

PART  m.    APPENDICES 


Extracts  from  Report  of  Forest  Service. 

Open-Tank  Experiments  on  Western  Yellow  Pine. 
Open-Tank  Experiments  on  Western  Red  Cedar. 

Report  of  German  Government — Telegraph  Department. 
Relative  Life  and  Value  of  Wood  Poles. 


EXTRACT  FROM  REPORT  OF  FOREST  SERVICE— OPEN- 
TANK  EXPERIMENTS  ON  WESTERN  YELLOW 
PINE  AND  WESTERN  RED  CEDAR 


TABLE  94 

POLE  TREATMENTS,  WESTERN  YELLOW  PINE 

Creosote  —  Open  Tank 

Time  of  Cutting 

Number 
Poles 
Averaged 

Absorption 
per  Cubic 
Foot 
Pounds 

Penetration 
Inches 

Moisture 
Content; 
Per  Cent, 
of  Green 
Weight  Lost 

Fall    .. 

11 

15.03 

4.3 

48.0 

Winter  

22 

11.03 

2.7 

51.5 

Summer  

2 

1.92 

M 

55.2 

Spring  (seasoned)    . 

3 

12.20 

3.4 

50.1 

Spring     (nearly     sea- 

soned)    

4 

11.08 

3.03 

50.0 

42 

13.02 

3.08 

50.5 

In  the  tables  throughout  the  report  the  absorption  is  given  in 
pounds  per  cubic  foot  of  the  treated  section  of  the  pole.  The  lower 
seven  feet  of  the  poles  contain  on  an  average  6.25  cubic  feet.  The 
penetration  is  given  in  inches  at  a  point  about  five  feet  from  the  butt 
of  the  pole. 

The  following  points  were  brought  out : 

1.  The  time  of  cutting  the  poles  shows  a  marked  influence  on 
absorption.     Summer-cut  poles  are  difficult  to  treat,   while   the 
Autumn-cut  takes  the  preservative  most  readily. 

2.  Good  absorption  can  be  secured  without  heating  the  oil  to 
temperatures  resulting  in  evaporation  of  the  creosote.     130  degrees 
Fahrenheit  was  used  as  a  maximum  temperature  with  good  results. 

An  average  absorption  of  13  pounds  per  cubic  foot,  and  a  penetra- 
tion of  3  inches  was  secured  by  this  treatment. 

These  poles  have  a  heavy  treatment.  The  wood-cells  are  full  of 
free  oil,  and  as  the  poles  were  removed  from  the  cold  oil  they  carried 
large  amounts  of  it  on  their  surface,  much  of  which  is  wasted. 

In  an  effort  to  overcome  these  disadvantages,  the  next  series  of 
treatments  were  given  as  the  preceding  series  except  that  the  oil 
was  again  heated  to  about  200  degrees  Fahrenheit  several  hours 
before  the  poles  were  removed.  The  object  of  the  reheating  is  to 
overcome  this  objection. 

The  results  are  presented  in  the  following  table:     (Table  95.) 

[655] 


Sec.  9 


WOOD  PRESERVATION 


TABLE  95 

POLE  TREATMENTS,  WESTERN  YELLOW  PINE 
Creosote  —  Open  Tank 

Time  of 
Cutting 

Number 
Poles 
Averaged 

Absorption 
per  Cubic  Foot 
(Pounds) 

Penetration 
(Inches) 

Moisture  Content; 
Per  Cent  of  Green 
Weight  Lost 

Fall  
Winter.  .  .  . 
Summer  .  .  . 
Spring  
(seasoned) 
Average  .  .  . 

9 
14 
20 

13 
56 

14.16 
5.45 
7.10 

11.67 
8.88 

5.25 
1.3 
2.2 

4.3 
3.3 

54 
52 
54 

54 
53 

It  is  apparent  that,  with  the  exception  of  the  Summer-cut  poles, 
each  cut  has  taken  up  less  oil  per  cubic  foot.  The  average  penetra- 
tion is  better  than  in  the  series  in  which  the  poles  were  not  reheated. 

The  average  absorption  of  8.9  pounds  of  oil  per  cubic  foot  with  a 
penetration  of  3.3  inches  at  the  ground  line  is  a  satisfactory  amount 
of  oil  for  the  result  secured.  Further,  when  poles  are  removed  hot 
from  the  oil,  the  outer  coating  of  oil  which  they  carry  on  their  sur- 
face, is  drawn  into  the  pole  by  the  interior  contracting  air  before  it 
reaches  the  ground  from  the  derrick. 

Borings  in  poles  treated  in  this  manner  show  that  the  outer  part 
of  the  wood  is  free  from  excess  oil  for  a  depth  up  to  two  inches, 
while  in  the  lower  part  of  the  boring  creosote  is  found  free  in  con- 
siderable quantity. 

The  third  plan  tried  with  a  single-tank  system  consisted  in  heating 
the  poles  in  hot  creosote  several  hours  and  allowing  the  oil  to  cool 
about  20  degrees,  which  required  an  hour,  and  then  removing  the 
poles  from  the  partially  cooled  oil. 

The  20  degrees  fall  in  temperature  draws  in  a  small  quantity  of 
oil.  The  pole  being  now  removed  and  allowed  to  cool  to  air  tem- 
perature the  contracting  air  in  the  wood  draws  the  free  oil  in  very 
deep,  coating  each  passageway  as  it  sinks  in  until  no  free  oil  is  left 
in  the  cells.  This  secures  the  greatest  protection  for  the  smallest 
amount  of  creosote.  The  treatment  is  very  successful,  resulting 
in  as  deep  a  penetration  as  3  inches  with  5  pounds  of  oil  per  cubic 
foot  of  wood. 

The  preceding  results  we're  secured  by  a  single  bath  treatment. 
Much  time  can  be  saved  with  an  equipment  permitting  two  baths 
of  the  preservative,  one  hot  and  one  cold.  This  may  be  accomplished 
by  two  tanks  or  an  arrangement  for  changing  the  oil  in  the  single 
tank  quickly.  In  this  way  the  effect  of  the  previously  described 
18-hour  treatments  can  be  secured  in  five  hours,  or  less. 

In  the  dry  weather  of  Summer,  if  the  poles  are  thoroughly  seasoned, 

[  656  ] 


WOOD  PRESERVATION  Sec.  9 

penetrations  of  two  to  three  inches  with  six  pounds  of  oil  per  cubic 
foot  can  be  secured  by  heating  the  poles  for  one  hour  in  oil  at  180 
degrees  Fahrenheit  and  then  plunging  them  into  air-cold  oil  for  from 
two  to  five  minutes.  The  poles  are  removed  very  hot,  the  surface 
oil  is  immediately  drawn  in  and  the  poles  are  dry  before  they  strike 
the  ground. 

Other  variations  in  the  tank  treatment  are  possible. 

The  important  conclusions  to  be  drawn  from  the  tank  treating 
experiments  with  creosote  upon  western  yellow  pine  are: 

1.  Poles  should  be  well  seasoned  before  treatment  until  they  have 
lost  50  per  cent  of  their  green  weight. 

2.  Poles  should  be  separated  according  to  season  of  cutting  before 
treatment  if  possible.     Summer-cut  pine  poles  should  not  be  treated 
with  other  poles,  as  they  require  a  severer  treatment. 

3.  Very  old  dry  poles  should  not  be  treated  in  the  same  run  with 
timber  just  seasoned. 

4.  Seasoned  pine  can  be  very  successfully  treated  with  creosote 
with  absorptions  up  to  15  pounds  of  oil  per  cubic  foot  of  treated 
timber  and  penetrations  as  deep  as  five  inches. 

5.  The  desirable  form  of  treatment  is  an  empty-cell  treatment, 
which  coats  the  interior  of  the  walls  and  leaves  no  excess  of  oil  in 
the  wood. 

6.  The  above  treatment  can  be  given  with  six  pounds  of  oil  per 
cubic  foot  or  with  four  and  one-half  gallons  to  the  average  40-ft. 
8-in.  pole. 

7.  The  quantity  of  oil  used  caif  be  controlled. 

8.  The  time  of  treatment  will"  vary  according  to  the  moisture 
condition  of  the  timber  as  affected  by  relative  humidity  and  recent 
rains. 

9.  Seasoned  timber  can  be  very  readily  treated  with  creosote  in 
from  one  to  five  hours,  according  to  its  moisture  condition. 

10.  Green  and  half -seasoned  poles  cannot  be  creosoted  successfully. 

11.  Poles  not  well  seasoned  should  be  treated  by  heating  for  several 
hours  at  215  degrees  Fahrenheit  and  plunging  into  cold  oil  until  the 
poles  are  cold.     This  is  a  forceful  treatment,  and  the  result  will 
depend  upon  the  moisture  condition  of  the  poles. 

12.  The  treatment  is  best  applied  to  seasoned  poles  as  follows: 

a.  By  heating  the  poles  for  one  hour  at  180  degrees,  cooling  the 
oil  to  160  degrees,  reheating  to  200  degrees,  and  withdrawing  the 
poles  hot. 

b.  By  heating  the  poles  for  one  hour  at  180  degrees,  plunging  them 
in  cold  oil  for  five  minutes  and  removing. 

c.  By  heating  as  above  and  holding  in  cold  oil  until  desired  ab- 
sorption is  secured  and  then  removing. 

Tank  Treatments  with  Crude  Petroleum.  The  poles  in  the  table 
below  were  heated  in  crude  oil  at  200  degrees  Fahrenheit  for  two  or 
three  hours  and  then  allowed  to  cool  in  the  oil  over  night,  making  a 
total  time  of  treatment  of  18  hours. 

The  Fall-cut  poles  show  the  best  absorption.  The  average  ab- 
sorption of  the  other  cuts  is  3.68  pounds  per  cubic  foot  with  a  pene- 

[  657] 


Sec.  9 


WOOD  PRESERVATION 


TABLE  96 

POLE  TREATMENTS,  WESTERN  YELLOW  PINE 
Crude  Petroleum  —  Open  Tank 

Season  of 
Cutting 

Number 
Poles 
Average 

Absorption 
per  Cubic  Foot 
(Lbs.) 

Penetration 
(Inches) 

Moisture  Content  ; 
Per  Cent  of  Green 
Weight  Lost 

Fall 

13 
2 
2 

1 

6 
11 

13.47 
2.35 
3.94 

16.20 

2.36 
3.68 

2.7 
1.5 
1.5 

3.0 

1.13 
1.4 

55.7 
53.0 
55.0 

59.4 

50.7 
53.0 

Winter  .... 
Summer.  .  . 
Spring  .... 
(seasoned) 
Spring 
(partly 
seasoned) 
Average  .  .  . 

tration  of  1.4  inches.  A  six-hour  treatment  of  Fall-cut  poles,  con- 
sisting of  heating  for  three  hours  at  200  degrees  Fahrenheit,  cooling 
in  three  hours  to  160  degrees  Fahrenheit,  and  then  removing  the 
poles,  gave  an  average  absorption  of  9.27  pounds  per  cubic  foot  with 
1.25  inches  penetration. 
The  conclusions  respecting  tank  treatments  with  crude  oil  are : 

1.  Western  yellow  pine  must  be  thoroughly  seasoned,  not  less 
than  50  per  cent  of  the  original  green  weight   being  evaporated 
before  treatment  with  crude  oil. 

2.  Crude  oil  is  weakly  antiseptic,  and  should  therefore  be  used 
only  on  very  dry  timber  and  in  cell-filling  quantities. 

3.  From  three  and  one-half  to  13  pounds  of  oil  per  cubic  foot  of 
timber,  immersed  according  to  the  season  of  cutting,  can  be  forced 
into  seasoned  pine  with  penetrations  of  from  one  to  three  inches. 
Fall-cut  timber  treats  by  far  the  most  easily. 

4.  The  time  of  treatment  will  vary  from  six  to  eighteen  hours. 
Treatments  with  Creosote  and  Crude  Petroleum.     To  secure  an 

antiseptic-treated  surface  upon  poles  treated  with  crude  oil,  it  was 
proposed  to  give  the  hot  bath  in  creosote  and  the  cold  bath  in  crude 
oil.  Six  poles  treated  in  this  manner  gave  an  average  absorption 
of  five  pounds  of  oil  per  cubic  foot  of  timber  with  a  penetration  of  1.7 
inches. 

This  treatment  is  not  recommended,  for  it  is  difficult  to  keep  the 
amount  of  creosote  absorbed  as  low  as  desired.  Further,  it  is 
probable  that  the  crude  oil  mixes  with  the  outer  creosote  and  weakens 
the  strength  of  the  wood-cell  coating  of  creosote. 

Tank  Treatment  with  Zinc  Chloride.  The  table  below  shows  the 
result  of  holding  the  poles  at  170  degrees  to  200  degrees  Fahrenheit 
in  a  zinc  chloride  solution  for  two  to  three  hours  and  allowing  the 
poles  to  cool  with  the  solution.  The  treatments  were  started  with  a 

[  658  ] 


WOOD  PRESERVATION 


Sec.  9 


seven  per  cent  solution  of  the  salt  and  varied  to  a  point  showing  a 
specific  gravity  of  1.03.     (Table  97.) 


TABLE  97 

POLE  TREATMENTS,  WESTERN  YELLOW  PINE 
Zinc  Chloride  —  Open  Tank 

Season  of 
Cutting 

Number  of 
Poles 
Averaged 

Absorption 
per  Cubic  Foot 
(Pounds) 

Moisture  Content  ; 
Per  Cent  of  Green 
Weight  Lost 

20 
6 
6 
16 
48 

23.65 
17.70 
17.70 
11.04 
17.90 

56.2 
55.0 

MJ 

Winter  

Spring 

Average  

The  zinc  chloride  solution  is  the  most  readily  absorbed  of  any  of 
the  preservatives.  Borings  and  chemical  analyses  proved  that  pure 
zinc  chloride  was  present  in  large  quantities  at  a  depth  of  five  inches, 
and  that  in  many  poles  a  much  larger  quantity  was  present  than 
necessary.  The  use  of  hot  and  cold  baths  shortens  the  time  of 
treatment.  Three  hours  divided  between  a  bath  at  150  degrees 
Fahrenheit  and  a  cold  bath  resulted  in  an  absorption  of  12.5  pounds 
of  the  solution  per  cubic  foot.  Merely  standing  the  poles  in  a  cold 
solution  for  15  hours  gave  an  absorption  of  9.7  pounds  per  cubic 
foot  of  timber. 

The  conclusions  for  this  treatment  are: 

1.  Pine  should  be  well  seasoned  (at  least  50  per  cent  of  green 
weight  being  evaporated)  before  treatment  with  zinc  chloride. 

2.  Greener  timber  can  be  treated  with  this  preservative  than 
with  the  oils. 

3.  Seasoned  timber  can  be  treated  in  from  two  to  six  hours. 

4.  The  amount  of  zinc  chloride  per  cubic  foot  and  the  depth  of 
penetration  is  under  control  by  varying  the  strength  of  the  solution 
and  the  time  of  treatment. 

5.  The  water  of  the  zinc  chloride  solution  should  be  dried  out 
before  the  poles  are  set  in  the  soil.     Two  weeks  proved  sufficient 
to  evaporate  this  water. 

6.  There  is  no  difficulty  in  securing  an  absorption  of  one-half 
pound  of  pure  zinc  chlorides  per  cubic  foot,  the  usual  commercial 
practice.     This  can  be  secured  with  a  two  per  cent  to  three  per  cent 
solution  of  the  salt. 

Tank  Treatments  with  Creosote  and  Zinc  Chloride.  This  is  a 
combination  treatment  designed  to  secure  a  narrow  creosote-treated 
belt  of  wood  around  an  interior  full  of  zinc  chloride.  The  reasons 
for  this  treatment  lie  in  the  facts  that  zinc  chloride  Is  inexpensive 

[659] 


Sec.  9 


WOOD  PRESERVATION 


but  soluble  in  water  and  so  subject  to  leaching  out  of  the  wood, 
while  creosote  is  insoluble  and  stable  but  expensive. 

In  practice  the  treatment  is  effected  by  heating  the  poles  in  creo- 
sote and  cooling  them  in  zinc  chloride  solution,  which  passes  through 
the  creosoted  exterior  to  the  interior  of  the  pole.  Poles  were  suc- 
cessfully treated  in  this  manner. 

This  treatment  is  not  recommended,  because  of  the  great  difficulty 
experienced  in  controlling  the  amount  of  creosote  absorbed  in  the  hot 
bath  and  holding  it  to  a  minimum  in  very  dry  poles. 

Summary  of  Absorption  Results.  The  absorptions  tabulated 
below  present  the  actual  results  of  the  successful  classes  of  treat- 
ment discussed  in  the  preceding  pages:  (Tables  98,  99,  100.) 


TABLE  98 
AVERAGE  ACTUAL  RESULTS  SECURED 

Preservative 

Application 

Absorption  ; 
Pounds  per 
Cubic  Foot 

Penetration 
(Inches) 

Treatment 
Recommended 
Pounds  per 
Cubic  Foot 

Creosote  .... 
Creosote  .... 
Carbolineum 
Carbolineum 
Creosote  .... 
Creosote  
Crude  oil  .... 
Zinc  chloride 

Brush  —  1  coat 
Brush  —  2  coats 
Brush  —  1  coat 
Brush  —  2  coats 
Tank—  full  cell 
Tank  —  empty  cell 
Tank 
Tank 

.4 
.6 
.5 
.8 
13.0 
8.9 
3.5  to  10 
17.9  (solution) 

f 
I 

1  to  3 
Complete 

Same 
Same 
Same 
Same 
10 
6 
6 
£  Ib  zinc 
chloride 

TABLE  99 
WESTERN  YELLOW  PINE 
Estimated  Annual  Service  Charge  40-ft.  8-in.  Poles 

Species 

Treatment 

COST  OP 
POLES 

Esti- 
mated 
Average 
Life 
(Years) 

Equivalent 
Annual 
Charge  at 

5% 

Added  Life 
Necessary 
to  Pay  for 
Treatment 
(Years)t 

In 
Yard 

In 

Line* 

Cedar  
Yellow  Pine 
Yellow  Pine 
Yellow  Pine 
Yellow  Pine 

Yellow  Pine 
Yellow  Pine 
Yellow  Pine 

None 
None 
Crude  o. 
Creosote  brush 
Carbolineum 
brush 
Zinc  chloride 
Creosote  10  Ibs. 
Creosote  6  Ibs. 

$8.00 
5.00 
5.61 
5.19 

5.43 
5.54 
6.82 
6.25 

$11.00 
8.00 
8.61 
8.19 

8.43 
8.54 
9.82 
9.25 

10 
3 

4 

5 
9 
20 
20 

$1.425 
2.94 

2.55 

2.01 
1.20 
.78 
.74 

8 

8 

•a 

*  Including  framing,  hauling  and  erecting,  but  not  stepping,  shaving  or  painting, 
f  Estimating  the  life  of  untreated  pine  at  three  years. 

[  660  ] 


WOOD  PRESERVATION 


Sec.  9 


TABLE  100 

POLE   TREATMENT—  WESTERN   YELLOW    PINE—  COM- 

PARATIVE COSTS  OF  TREATMENT,  STANDARD 

40-FOOT  POLE,  WEIGHING  800  POUNDS, 
TREATING  6>i  CUBIC  FEET 

QUANTITY 

COST  OF  PRE- 
SERVATIVE 

Total 

Handling 

Cost  of 

Preservative 

Application 

Charge 

Treat- 

Per 
Cu.  Ft. 
Lbs. 

Per 
Pole 
Lbs. 

Per 
Pound 

Per 
Pole 

per  Pole 

ment  per 
Pole 

Creosote  .... 

Brush 

.4 

2.50 

$0.0235 

SO.  06 

$0.05 

$0.11 

1  coat 

Creosote  .... 

Brush 

2  coats 

.6 

3.75 

.0235 

.09 

.10 

.19 

Carbolineum 

Brush 

1  coat,. 

.5 

3.13 

.066 

.21 

.05 

.26 

Carbolineum 

Brush 

2  coats 

.8 

5.00 

.066 

.33 

.10 

.43 

Creosote  .... 

Tank 

10.0 

62.50 

.0235 

1.47 

.35 

1.82 

Creosote.  .  .  . 

Tank 

6.0 

37.50 

.0235 

.89 

.35 

1.24 

Crude  petro- 

leum   

Tank 

6.0 

37.50 

.007 

.26 

.35 

.61 

Zinc  chloride 

Tank 

.5 

3.12 

.06 

.19 

.35 

.54 

Creosote  and 

\ 

1.0 

6.25 

.0235 

.15 

\         35 

CO 

zinc  chloride 

/Tank 

.5 

3.12 

.06 

.19 

)       '35 

.69 

WESTERN  RED  CEDAR 

Tank  Treatments  with  Creosote.  Thoroughly  seasoned  cedar 
poles  of  the  Fall  and  Summer  cut,  treated  after  seasoning  to  23 
pounds  per  cubic  foot,  showed  an  average  absorption  of  seven  pounds 
per  cubic  foot  of  timber  immersed.  The  penetrations  varied  from 
.2  to  1.5  inches  and  averaged  .7  of  an  inch  at  a  point  corresponding 
to  the  ground  line  of  the  pole  in  service. 

These  figures  are  the  average  of  those  obtained  by  treating  126 
poles  in  a  single  bath  of  creosote  heated  to  200  degrees  Fahrenheit 
to  225  degrees  Fahrenheit  for  from  two  to  six  hours,  and  then  allow- 
ing the  poles  to  cool  in  the  oil  until  the  following  morning,  making  a 
total  time  of  treatment,  including  handling,  of  24  hours  or  one  run 
per  day. 

There  is  no  difference  in  the  absorption  of  Summer-cut  and  Fall- 
cut  poles  as  in  the  case  of  yellow  pine.  One  reason  for  this  fact  is 
that  cedar  is  all  heart-wood  except  an  outer  band  of  sap-wood  from 
one-half  to  one  and  one-half  inches  thick.  The  heart-wood  cannot 
be  penetrated  by  this  process,  but  the  narrow  sap-wood  band  of 
well-seasoned  poles  can  be  completely  filled  with  oil  irrespective  of 
the  season  of  cutting. 

[  66X] 


Sec.  9 


WOOD  PRESERVATION 


When  the  heart-wood  is  protected  by  a  band  of  sap-wood  filled 
with  creosote  the  pole  is  exceedingly  decay  resistant. 

In  order  to  reduce  the  time  of  treatment,  experiments  on  Fall-cut 
poles  seasoned  to  23  pounds  were  tried  with  hot  and  cold  tanks  of 
oil.  The  poles  were  heated  from  three  to  six  hours  in  the  hot  bath 
and  then  plunged  into  the  cold  bath  for  a  limited  period.  The  results 
are  tabulated  below:  (Table  101.) 


TABLE  101 

WESTERN  RED  CEDAR 

Absorption  of  Creosote 

Poles  seasoned  to  23  pounds  per  cubic  foot 

HOURS  OF  TREATMENT 

Number 
Poles 
Averaged 

Total 

Absorption 
(Pounds  per 
Cubic  Foot) 

Penetration 
(Inches) 

Hot 

Cold 

Bath 

Bath 

8 

3 

2 

1 

3.3 

.48 

4 

4 

3 

1 

2.5 

.35 

4 

4 

2 

2 

2.9 

.39 

6 

5 

4 

1 

3.8 

.45 

4 

6 

4 

2 

3.8 

.50 

126 

18 

Hot  bath  cooling  to 

7.0 

.70 

air  temperature 

Short  runs  can  apparently  be  made  with  success.  From  the 
tabulation  it  cannot  be  said  what  period  can  best  be  used  in  practice, 
but  it  is  safe  to  say  that  a  six-hour  run  will  result  in  an  absorption 
of  3.8  pounds  per  cubic  foot  and  a  penetration  of  one-half  inch. 

Winter-cut  poles  treated  with  creosote  after  seasoning  to  25  ^ 
pounds  per  cubic  foot  could  not  be  well  treated  in  short  runs.  Seven 
hours  in  the  hot  bath  followed  by  one-half  hour  in  the  cold  bath  gave 
an  average  absorption  of  but  1.6  pounds  of  oil  per  cubic  foot  and  a 
penetration  of  one-eighth  inch.  These  poles  were  best  treated  by 
leaving  them  in  the  tank  while  the  oil  was  heated  for  about  three 
hours,  cooled  two  hours,  reheated  two  hours,  and  then  permitted  to 
cool  over  night.  The  oil  absorbed  in  the  first  heating  and  cooling 
aids  in  the  second  heating  and  cooling.  Upon  22  poles  this  treat- 
ment resulted  in  an  average  absorption  of  4.4  pounds  of  oil  per  cubic 
foot  arid  a  penetration  of  one-third  inch. 

Two  and  three  hours'  heating,  and  allowing  the  poles  to  stand  over 
night  resulted  in  three  pounds  absorption  and  one-quarter  inch 
penetration.  It  can  be  readily  seen  that  poles  at  25^  pounds 
absorb  about  one-half  as  much  oil  as  when  they  are  seasoned  to  23 
pounds.  Further,  the  treatment  in  the  latter  case  is  much  shorter. 

[662] 


WOOD  PRESERVATION 


Sec.  9 


Experiments  with  the  Spring-cut  poles  proved  that  poles  seasoned 
to  but  28  pounds  cannot  be  successfully  creosoted. 

A  few  old,  dry  poles  from  a  pile  in  the  Pacific  Electric  Company's 
yards  were  treated  to  show  the  possibilities  with  thoroughly  seasoned 
poles.  The  results  follow:  (Table  102.) 


1 

FABLE  102 

Treatment 

Absorption 

Hot  Bath  (Hours) 

Cold  Bath 
(Hours) 

(Pounds  per 
Cubic  Foot) 

(Inches) 

4 

o 

2/3 

V* 

3 

20  minutes 

3 

H 

5 

5       " 

4 

*>/ 

1  
2 

1 
1 

7 
5 

i 

3  

1 

5 

£ 

The  important  conclusions  are: 

1.  Poles  should  be  seasoned  to  25  pounds  per  cubic  foot  before 
creosoting.     Better  results  are  secured  after  seasoning  to  23  pounds 
per  cubic  foot. 

2.  The  time  required  for  creosoting  timber  seasoned  to  25  pounds 
per  cubic  foot  will  vary  from  seven  to  24  hours  according  to  the 
result  desired.     Two  runs  per  day  per  tank  can  be  made,  one  giving 
an  absorption  of  one  and  one-half  pounds  per  cubic  foot,  and  the 
second  an  absorption  of  three  pounds,  or  one  daily  run  may  be  made 
with  an  absorption  of  four  and  one-half  pounds  per  cubic  foot.     As 
the  poles  become  dryer  the  absorptions  increase. 

3.  The  best  absorption  and  penetration  is  secured  when  the  poles 
are  seasoned  to  a  weight  of  23  pounds  per  cubic  foot.     At  this  stage 
the  sap-wood  can  be  completely  filled  with  creosote  with  about  five 
gallons  of  oil  per  average  pole. 

4.  Poles  seasoned  to  23  pounds  per  cubic  foot  may  be  creosoted 
in  six  hours  and  less  with  an  absorption  of  3.8  pounds  per  cubic  foot 
and  a  penetration  of  one-half  inch.     This  amounts  to  about  three 
gallons  of  oil  per  pole. 

5.  The  sap-wood  of  cedar  poles  seasoned  to  23  pounds  can  be 
completely  filled  in  a  24-hour  single  bath  treatment  with  an  absorp- 
tion of  seven  pounds  per  cubic  foot  or  approximately  five  gallons  of 
oil  per  pole. 

Tank  Treatments  with  Crude  Petroleum.  Cedar  cannot  be  suc- 
cessfully impregnated  with  crude  oil  in  an  open  tank.  Even  with 
thoroughly  seasoned  poles  but  slight  absorption  and  penetration 
can  be  obtained — barely  more  than  a  coating  of  oil. 

Tank  Treatments  with  Zinc  Chloride.    Treatments  upon  the 

[  663  ] 


Sec.  9  WOOD  PRESERVATION 

partially  seasoned  poles  of  the  Spring-cut  with  a  water  solution  of 
zinc  chloride  prove  that  three  pounds  of  solution  per  cubic  foot  can 
be  forced  into  poles  seasoned  only  to  a  weight  of  31  pounds  per  cubic 
foot.  This  required  a  24-hour  treatment  consisting  of  heating  several 
hours  at  210  degrees  Fahrenheit  and  allowing  the  poles  to  cool  in 
the  solution  over  night. 

Poles  seasoned  to  25  pounds  per  cubic  foot  absorbed  about  four 
pounds  of  seven  per  cent  solution  per  cubic  foot  in  short  runs,  con- 
sisting of  two  hours  in  each  bath  or  a  total  of  four  hours.  One 
hundred  and  three  poles,  seasoned  to  23  pounds  per  cubic  foot, 
treated  in  a  zinc  chloride  solution  heated  to  210  degrees  Fahrenheit 
for  one  to  four  hours  and  allowed  to  cool,  averaged  an  absorption 
of  four  pounds  per  cubic  foot.  This  treatment  ft  unnecessarily 
long  for  poles  so  well  seasoned.  The  same  results  apparently  can  be 
obtained  in  four  hours  by  hot  and  cold  baths.  In  these  treatments 
the  strength  of  the  solution  varied  from  three  per  cent  to  10  per  cent. 

The  conclusions  for  this  preservative  are: 

1.  Greener  poles  may  be  treated  with  zinc  chloride  solution  than 
with  creosote      Poles  seasoned  only  to  31  pounds  per  cubic  foot  will 
absorb  three  pounds  of  solution  per  cubic  foot  in  a  24-hour  treatment. 

2.  The  strength  of  the  treatment  can  be  controlled  by  the  amount 
of  the  zinc  chloride  in  solution.     One-half  pound  of  the  pure  chloride 
for  each  cubic  foot  of  timber  immersed  is  sufficient. 

3.  Poles  seasoned  to  25  pounds  per  cubic  foot  and  below  can  be 
quickly  treated  in  four  hours  with  four  pounds  of  solution. 

Tank  Treatments  with  Creosote  and  Zinc  Chloride.  This  treat- 
ment should  be  used  only  on  poles  seasoned  to  at  least  25  pounds 
per  cubic  foot.  At  this  stage  poles  held  in  a  bath  of  creosote  at  212 
degrees  Fahrenheit  for  one  hour  or  more,  and  then  plunged  into  a 
solution  of  zinc  chloride,  will  absorb  about  two-thirds  pound  of 
creosote  per  cubic  foot  in  the  hot  bath  and  three  and  one-third  pounds 
of  solution  in  the  cold  bath. 

Twelve  zinc-treated  poles  which  had  evaporated  the  water  of  the 
solution  were  brush-treated  with  creosote,  absorbing  about  half- 
pound  of  oil  per  cubic  foot  in  two  coats. 

Poles  freshly  treated  in  a  zinc  solution  will  not  absorb  creosote 
upon  being  brush  treated  or  plunged  into  a  tank  of  oil. 

REPORT  OF  GERMAN  GOVERNMENT— TELEGRAPH 
DEPARTMENT 

The  Relative  Life  and  Value  of  Wooden  Poles 
BY  GEH.  OBER-POSTRAT  CHRISTIANI,  BERLIN1 

The  Government  telegraph  department  has  in  its  collection  of 
statistics  a  rich,  but  unfortunately  undeveloped,  field  for  inquiry 
as  to  the  life  of  wooden  telegraph  poles.  All  the  upper  postal  direct- 
ors transmit  annually  to  the  head  office  reports  as  to  the  condition 
at  the  beginning  of  the  year  of  the  wooden  poles  standing  in  the  lines, 

»Archiv.  fur  Post  und  Telegraphie:    Nr.  16  Berlin,  August,  1905. 

[664] 


WOOD  PRESERVATION  Sec.  9 

likewise  the  additions  due  to  new  construction,  change  of  route,  or 
replacement,  and  on  the  other  hand,  those  lost  from  decay  or  other 
causes.  These  reports  which  cover  the  entire  territory  of  the  de- 
partment are  comprehensively  summarized. 

These  statistics  go  back  for  the  North-German  and  even  the 
Prussian  telegraph  systems  to  1852,  and  thus  cover  a  period  of  more 
than  50  years.  These  statistics  are  of  particular  value,  because 
the  figures  are  separated  as  between  untreated  and  treated  poles, 
and  furthermore  separated  as  to  the  different  treatments  which  have 
been  used,  as  copper  sulphate,  zinc  chloride,  dead  oil  of  coal-tar,  and 
corrosive  sublimate. 

The  thought  then  arises  to  calculate  from  this  abundant  material 
the  average  life  of  the  different  kind  of  poles  and  to  draw  conclu- 
sions therefrom  as  to  the  economical  value  of  the  different  treatments. 
The  occasion  for  doing  this  in  a  thorough  manner  has  not  previously 
arisen.  Although  Archive  No.  23  for  1883  contained  a  paper  on 
"The  Average  Life  of  Poles  in  the  Government  Telegraph  Lines" 
it  is  merely  a  reprint  of  the  statistics  collected  for  the  official  year 
1879-1880  and  is  without  value  as  a  basis  for  determining  the  average 
life.  Another  paper,  by  Kohlman,  covering  the  subject  matter, 
is  to  be  found  in  Archive  No.  5  for  1890,  under  the  title,  "The 
Different  Processes  of  Protecting  Wood  Against  Decay  With  Special 
Reference  to  the  Conditions  Which  Are  Involved  in  the  Treatment 
of  Telegraph  Poles." 

This  noteworthy  paper  gives  a  detailed  statement  of  the  ordinary 
methods  of  treatment  under  the  conditions  prevailing  at  that  time, 
and  states  among  other  things  that  fir  (kieferne)  poles  of  the  usual 
dimensions  have  lives  approximately  as  follows: 

Untreated  poles  ................................  4  to    5  years 

Poles  treated  with  copper  sulphate  ...............  10  to  14 

"    zinc  chloride  ..................  8  to  12 

"    dead  oil  of  coal-tar  ............  15  to  20 

"    corrosive  sublimate  ............  9  to  10 

This  statement,  however,  is  not  backed  up  with  adequate  figures. 
We  shall  see  that  different  average  lives  follow  from  Government 
statistics,  the  publication  of  which,  together  with  the  data  on  which 
they  are  based,  should  fill  a  gap  in  the  literature  of  the  subject. 

First  of  all  we  give  an  idea  of  the  development  of  the  network 
of  lines  upon  which  these  observations  have  been  made  by  means 
of  the  accompanying  tabulation  of  the  telegraph  poles  in  the  lines 
at  the  close  of  each  vear  since  1852.  (Table  103.) 

The  great  proportion  of  poles  treated  with  copper  sulphate  is 
apparent.  Expressed  as  percentage  per  100  poles  there  were  at  the 
close  of  1903  treated  with: 

Copper  sulphate  .......................................  89.9 

Zinc  chloride  ..........................................  0.4 

Dead  oil  of  coal-tar  ................  .  ...................  3.0 

Corrosive  sublimate  ....................................  5.5 

Other  Methods  ......................  ..................  0.1 

And  Untreated  ........................................  1.1 


Total  ...........................................     100.0 

[665] 


Sec.  9 


WOOD  PRESERVATION 


TABLE  103 

CHANGE  IN  THE  NUMBER  OF  TELEGRAPH  POLES 

FROM  1852  TO  1903 

At  the 

POLES  WERE  STANDING  IN  THE  LINES 

Close  of 

Treated  With 

the 

Official 
Year 

Copper 
Sulphate 

Zinc 
Chloride 

Dead  Oil  of 
Coal-Tar 

Corrosive 
Sublimate 

Untreated 

1852 

1,983 

1854 

1,990 

1856 

5,751 

'942 

1857 

6,723 

2 

942 

1858 

"562 

8,185 

2 

"105 

952 

1859 

3,241 

12,318 

93 

105 

952 

1860 

12,136 

18,783 

566 

105 

960 

1861 

25,048 

28,323 

2,501 

379 

1,041 

1862 

46,246 

44,983 

3,270 

2,072 

1,420 

1863 

65,619 

31,973 

7,661 

2,353 

1,462 

1864 

76,926 

50,233 

13,268 

2,636 

2,263 

1865 

81,702 

57,810 

20,864 

2,893 

2,891 

1866 

80,811 

64,005 

29,028 

2,893 

3,574 

1867 

79,378 

71,654 

41,117 

3,008 

6,877 

1868 

77,308 

75,447 

70,224 

3,425 

9,943 

1869 

75,820 

78,847 

86,204 

4,390 

13,165 

1870 

72,828 

81,125 

97,704 

5,854 

15,510 

1871 

70,545 

82,574 

116,427 

10,924 

19,321 

1872 

69,940 

85,089 

135,630 

12,884 

23,535 

1873 

75,878 

92,663 

155,073 

15,411 

28,393 

1874 

96,767 

107,074 

159,368 

18,803 

28,638 

1875 

137,149 

100,411 

160,678 

26,437 

30,930 

1876 

188,615 

88,668 

160,016 

31,283 

29,811 

1877 

258,221 

90,828 

163,857 

41,995 

29,044 

1878 

350,202 

77,679 

156,044 

67,474  ) 

1879 

429,834 

68,357 

148,323 

77,571 

T» 

1880 
1881 

482,878 
522,572 

56,941 
49,519 

138,683 
134,792 

81,111 
81,849  1 

Uata 
Missing 

1882 

566,906 

42,551 

129,897 

80,321 

1883 

605,504 

37,318 

128,582 

81,616 

21,404 

1884 

613,604 

32,317 

124,603 

85,272 

19,277 

1885 

739,160 

27,342 

123,976 

88,047 

16,049 

1886 

803,493 

23,671 

119,093 

91,393 

12,730 

1887 

833,636 

19,560 

113,419 

94,718 

9,957 

1888 

943,348 

17,121 

110,678 

97,131 

7,779 

1889 

1,018,529 

16,723 

107,747 

95,751 

6,259 

1890 

1,105,656 

15,642 

103,999 

92,278 

5,436 

1891 

1,134,051 

14,429 

100,326 

88,407 

4,698 

1892 

1,26?,842 

16,791 

96,684 

83,845 

4,156 

1893 

1,351,683 

16,643 

92,099 

78,580 

16,421 

1894 

1,439,379 

17,296 

89,332 

74,330 

21,962 

1895 

1,515,234 

17,599 

85,577 

66,957 

31,161 

1896 

1,585,001 

17,851 

83,640 

59,298 

42,652 

1897 

1,670,985 

16,949 

82,209 

52,967 

51.300 

1898 

1,784,312 

16,579 

81,306 

47,392 

55,257 

1899 

1,917,166 

15,816 

84,505 

56,652 

60,914 

1900 

2,111,952 

15,089 

90,338 

74,770 

57,332 

1901 

2,278,021 

13,965 

88,963 

91,035 

49,015 

1902 

2,428,930 

13,469 

88,254 

125,196 

39,830 

1903 

2,560,412 

11,689 

86,818 

156,818 

30,895 

WOOD  PRESERVATION 


Sec.  9 


It  might  be  mentioned  here  that  the  administration  purchases 
almost  its  entire  supply  of  wooden  poles  green  and  treats  them  at 
its  own  plants  with  copper  sulphate.  Moreover,  for  about  five 
years,  if  only  as  a  makeshift,  it  has  provided  for  the  delivery  of 
kyanized  poles  by  outside  contractors.  The  two  above-mentioned 
treatments — the  cylinder  treatments — with  zinc  chloride  and  with 
dead  oil  of  coal-tar  have  on  the  other  hand — excepting  occasional 
experiments  with  tar-impregnated  poles — been  discontinued. 

In  order  to  obtain  the  total  number  of  telegraph  poles  which  have 
served  as  a  basis  for  our  tables,  we  have  added  to  the  poles  which 
were  in  the  lines  at  the  end  of  1903,  the  total  number  of  poles,  which, 
on  account  of  decay  and  other  causes,  have  been  replaced  since  1852. 
These  totals  are  tabulated  in  the  following  table:  (Table  104.) 


TABLE  104 
TOTAL  NUMBER  OF  POLES  UNDER  OBSERVATION 

Treatment 

Poles 
Standing 
in  the 
Line  at 
the  End 
of  1903 

NUMBER  OF  POLES  WHICH 
HAVE  BEEN  REMOVED 
BETWEEN  1852-1903 

Total 
No.  of 
Poles 
Under 
Obser- 
vation 

On 
Acoount 
of  Decay 

From 
Other 
Causes 

All  To- 
gether 

Copper  sulphate  
Zinc  chloride 

2,590,412 
11,689 
85,818 
156,818 
2,108 
30,895 

663,069 
172,822 
83,630 
113,577 

76,813 

536,955 
33,388 
92,049 
23,516 

15,257 

1,200,024 
206,210 
175,679 
137,093 

92,070 

3,760,436 
217,899 
262,497 
293,911 
2,108 
122,965 

Dead  oil  coal-tar  
Corrosive  sublimate  
Other  treatments  
Untreated  

Total  

2,848,740 

1,109,911 

701,165 

1,811,076 

4,659,816 

During  52  years,  4,659,816  telegraph  poles  of  different  kinds  have 
accordingly  been  under  observation.  Such  a  long  period  of  observa- 
tion and  such  an  extraordinarily  large  number  of  observations  which 
have  occurred  under  the  most  varying  local  conditions  have  permitted 
the  calculation  of  mean  lives  which  can  lay  claim  to  general  validity. 

The  restriction  to  a  single  line  or  to  a  shorter  period  of  observation 
would  afford  no  guarantee  for  the  reliability  of  the  average  figures. 
For,  on  the  one  hand,  the  life  of  poles  depends,  for  the  same  kind  of 
treatment,  to  a  large  degree  on  the  dimensions  as  well  as  on  the 
species,  on  the  age  and  on  the  conditions  of  growth  of  the  tree  from 
which  the  poles  are  obtained;  on  the  other  hand,  on  the  character 
of  the  soil  in  which  they  are  set  and  on  the  climatic  influences  to 
which  they  are  exposed.  This  diversity  of  conditions  could  not  but 
make  itself  felt  in  a  small  series  of  observations;  it,  however,  is 

[667] 


Sec.  9 


WOOD  PRESERVATION 


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[668] 


WOOD  PRESERVATION 


Sec.  9 


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[  669  1 


Sec.  9 


WOOD  PRESERVATION 


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[  670] 


WOOD  PRESERVATION  Sec.  9 

compensated  if  we  can  give  the  inquiry  as  broad  a  scope  as  was  at 
our  command  for  the  calculations  in  question. 

It  must  be  kept  in  mind,  however,  that  the  figures  for  the  average 
lives  can  only  be  considered  as  of  reliable  value  for  comparative 
purposes,  when  the  new  poles  added  each  year  to  the  lines  are  ap- 
proximately constant.  With  increasing  setting,  the  calculated 
average  lives  will  be  too  small  since  the  increasing  number  of  the 
premature  removal  of  the  recently  set  poles  depresses  the  result, 
while  a  decrease  or  a  discontinuance  of  the  yearly  growth  gives 
more  favorable  value  to  the  figures. 

Unfortunately,  although  as  may  easily  be  conceived,  the  method 
according  to  which  the  record  of  the  deteriorated  poles  was  obtained 
did  not  remain  unchanged  during  the  five  decades.  We  must,  on 
that  account,  divide  our  calculations  into  two  distinct  periods — 
from  1852  to  1882,  and  from  1883  to  1903.  For  the  purpose  of  this 
study,  it  was  necessary  to  recompute  a  portion  of  the  yearly  tabula- 
tions; still  the  final  result  was  obtained  without  constraint  and  the 
correctness  of  the  final  result  has  not  been  invalidated  on  account 
of  the  variation  in  the  basis  figures. 

It  appears  expedient  to  refer  briefly  to  the  fundamental  difference 
in  the  methods  which  have  been  used  for  collecting  the  statistics 
for  the  two  periods.  During  the  first  three  decades  the  number  of 
poles  standing  in  the  lines  was  annually  recorded,  and  the  annual 
removals  recorded,  until  all  the  poles  placed  during  a  certain  year 
had  been  removed  from  the  lines;  then  the  proper  tabulation  could 
be  prepared  and  the  average  life  determined. 

That  method  was  free  from  objection  and  had  only  one  drawback, 
that  each  year  a  new  summary  had  to  be  made  and  which  had  to  be 
continued. 

The  increasing  inconvenience  from  year  to  year  and  the  lack  of 
ready  comprehensiveness  which  arose  from  the  large  number  of 
tabulations,  may  well  be  given  as  the  reason  why  in  1883  the  statistics 
were  substantially  simplified  and  recorded  in  another  form.  The 
new  scheme  collects  together  the  removals  of  each  year  and  permits 
the  average  life  to  be  calculated  as  the  mean  for  all  poles  replaced 
during  the  year  in  question.  The  individual  lives  of  the  older  poles 
would  only  be  separately  given  up  to  19  years,  while  the  poles  of 
longer  life  could  be  collected  in  a  table  for  "20  years  and  over." 
The  values  determined  in  this  manner  are  also  affected  by  one  in- 
accuracy, which,  moreover,  can  only  be  allowed  for  by  interpolation. 

From  the  preceding  compilation  the  number  of  poles  removed 
on  account  of  rot  and  their  length  of  service  is  given  in  Table  105  for 
the  period  from  1852  to  1882,  and  in  Table  106  for  the  years  1882  to 
1903.  In  both  tables  the  total  duration  in  terms  of  pole  years, 
that  is  the  product  of  the  number  of  poles  and  the  actual  lives,  is 
given. 

Table  106,  covering  the  period  from  1883  to  1903,  requires  a  cor- 
rection, because  poles  having  a  life  of  twenty  years  and  over  have 
only  been  credited  with  a  life  of  twenty  years.  In  order  to  correct 
this  error,  as  above  stated,  to  some  degree,  a  retabulation  107  has 

[671] 


Sec.  9 


WOOD  PRESERVATION 


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[  672  ] 


WOOD  PRESERVATION  Sec.  9 

been  made,  which  has  been  based  on  the  assumption  that  the  poles 
in  question  are  capable  of  offering  a  resistance  of  about  double  the 
average  life  which  poles  of  that  type  would  attain :  instead  of  twenty 
years  the  treated  poles  would  have  a  life  as  follows : 

Copper  sulphate 25  years 

.    Zinc  chloride 25 

Dead  oil  of  coal-tar 35       " 

Corrosive  sublimate 28       " 

and  untreated  poles  25  years.  The  surplus  thus  obtained  has 
accordingly  been  added  to  the  pole  years  already  found. 

We  have  now  only  to  summarize  the  three  Tables,  105,  106  and 
107,  and  from  the  sum  total  calculate  the  average  life  of  the  dif- 
ferent types  of  treated  poles.  This  is  tabulated  in  Table  108. 

The  results  thus  determined  are  of  particular  interest,  as  the  as- 
sumption previously  generally  held  considered  that  the  most  efficient 
treatment  next  to  dead  oil  of  coal-tar  was  copper  sulphate.  Accord- 
ing to  Table  108,  however,  this  idea  is  proved  to  be  erroneous,  as  in 
fact  during  the  elapsed  50  years  of  all  treated  poles,  those  treated 
with  copper  sulphate  have  given  the  shortest  average  life.  Contrary 
to  expectations,  corrosive  sublimate  gives  the  most  efficient  treat- 
ment next  to  the  unrivaled  dead  oil  of  coal-tar,  and  the  equally 
misjudged  zinc  chloride  comes  next,  also  ahead  of  copper  sulphate. 
The  untreated  poles  show  up  quite  favorably  as  regards  their  dura- 
bility. The  reason  for  this  is  that  during  the  first  thirty  years  oak 
poles  were  used  in  excess,  and  they  often  remained  in  the  lines  over 
20  years. 

The  differences  which  appear  are  striking  if  the  average  lives  of 
each  kind  of  pole  are  determined  from  each  of  the  Tables  105  and  106. 
The  values  thus  obtained  could,  however,  make  no  pretense  as  being 
reliable;  although  in  general  it  is  noticeable  that  wooden  poles  now 
attain  a  longer  life  than  formerly  An  examination  of  the  yearly 
values  in  Table  106  leads  to  a  similar  observation.  This  is  not  sur- 
prising in  the  case  of  those  poles  which  have  been  treated  with  dead 
oil  of  coal-tar  and  zinc  chloride,  for  they  date  from  the  earlier  times. 
Only  the  most  durable  samples  of  their  kind  are  now  standing  in  the 
lines,  and  when  replaced  enter  the  records  with  long  lives.  For  poles 
treated  with  copper  sulphate  and  corrosive  sublimate,  the  result  can 
hardly  mean  other  than  that  substantial  progress  has  been  made  in 
the  method  of  treatment.  A  further  indication  may  be  found 
therein  which  points  to  a  greater  efficiency  in  the  maintenance  work. 
In  any  case,  we  are  justified  in  concluding  that  the  poles  which  are 
now  being  installed  in  the  lines  will  attain  a  greater  average  life 
than  the  above  average  figures. 

The  average  lives  are  evidently  not  sufficient  to  estimate  the 
economical  value  of  the  different  treatments,  but  we  must  further 
take  into  consideration  the  cost  of  manufacture,  the  freight  and 
the  cost  of  erection  of  the  poles.  The  latter  figure,  which  should 
include  a  proper  amount  for  the  pole  equipment,  is  the  same  for  all 
treatments  with  the  exceptions  of  the  poles  treated  with  dead  oil 

22  [  673  ] 


Sec.  9 


WOOD  PRESERVATION 


of  coal-tar,  which,  on  account  of  their  greater  weight  and  well-known 
inconvenience  in  handling,  cause  higher  charges  for  freight  and  labor. 
The  following  table  gives  the  economical  value  of  the  different  kinds 
of  treatment  as  computed  on  the  above  basis.  The  manufacturing 
and  erection  (including  freight)  charges  are  based  on  1903  prices. 
The  economical  value  is  reduced  for  simplicity  of  comparison  to  the 
charge  per  cubic  meter  (of  pole)  per  year.  (Table  109.) 


TABLE   109 

ECONOMICAL  VALUE  FOR  THE  DIFFERENT  TREAT- 

MENTS 

Kind  of  Treatment 

Aver- 
age 
Life 

(Years) 

Manufac- 
ture 

Cost  per 
Cubic 
Meter  for 
Freight 
and 
Erection 

Total 

Cost  per 
Cubic 
Meter  per 
Year 

Mark 

Pf. 

Mark 

Pf. 

Mark 

Pf. 

Mark 

Pf. 

Copper  sulphate  .  .  . 
Zinc  chloride  
Dead  oil  coal-tar  .  .  . 
Corrosive  sublimate 
Untreated  

11.7 

11.9 
20.6 
13.7 
7.7 

28 
28 
36 
32 
20 

96 
12 
93 
89 
80 

20 
20 
25 
20 
20 

48 
48 
61 
52 
40 

96 
12 
93 
89 
80 

4 
4 
3 
3 
5 

19 
05 
01 
86 
30 

The  average  annual  cost  in  the  last  column  is  evidently  only  an 
approximate  value,  because,  while  the  estimated  lives  extend  over 
a  series  of  years,  the  estimated  costs  only  relate  to  the  last  year  of 
observation.  It  follows  in  general,  however,  that  the  order  of  the 
treatments  as  regards  their  economical  value  is  the  same  as  the 
order  of  the  average  lives.  Dead  oil  of  coal-tar  stands  in  first  place. 
For  this  reason  it  is  to  be  regretted  that  as  yet  no  remedy  has  been 
found  to  counteract  the  disadvantages  attendant  with  its  use.  Poles 
treated  with  corrosive  sublimate  stand  in  second  place  and  its 
superiority  over  zinc  chloride  and  copper  sulphate  treatments  can 
no  longer  be  doubted.  The  most  unfavorable  position  in  this 
economical  relation  is  held  by  untreated  poles,  the  annual  cost  of 
which  is  nearly  twice  as  much  as  the  best  treated  pole. 


[674] 


SECTION  10 

RECOMMENDATIONS  OF  THE   COMMITTEE 

ON  OVERHEAD  LINE  CONSTRUCTION, 

1914 


PART  I 
SPECIFICATIONS  FOR  METHODS  OF  CONSTRUCTION 


PART  II 
METHODS  OF  SECONDARY  SYSTEM  WORK 


COMMITTEE  ON  OVERHEAD  LINE  CONSTRUCTION 

THOMAS  SPROULE,  Chairman. 
R.  D.  COOMBS,  W.  T.  OVIATT, 

H.  M.  HOPE,  F.  B.  H.  PAINE, 

G.  H.  LUKES,  F.  L.  RHODES, 

FARLEY  OSGOOD,  PAUL  SPENCER, 

C.  W.  STONE. 


SECTION  10 

PART  I— SPECIFICATIONS  FOR  METHODS  OF 
CONSTRUCTION 


TABLE  OF  CONTENTS 

ARTICLE 

Scope 1 

Poles  and  Pole  Setting 

Specification 2 

Height 3 

Trimming 4-5 

Cross- Arm  Gains 6 

Reverse  or  Buck- Arm  Gains 7-8 

Painting 9 

Pole  Numbering 10 

Rights-of-Way 11 

Street  Rights-of-Way 12 

Back  Yard  Rights-of-Way 13 

Locating  Poles  on  Street 14 

Spacing • 15 

Street  Crossings 16 

Heavy  Poles .* 17 

Clearing  Obstacles 18 

Line  Level 19 

Curb  Line 20 

Pole  Setting 21  to  20 

Crib  Bracing 27 

Artificial  Foundation 28 

Quicksand 29 

Poles  Located  in  Rock 30 

Protection 31 

Pole  Steps 

Poles  to  be  Stepped 32 

Galvanized  Iron  Pole  Steps 33 

Location  on  Pole , 34-35 

Cross-arms 

Cross-arms 3G 

Size  Arms  to  Use 37 

Painting  and  Treating 38 

Cross-arm  Bracing 39 

Fitting  Cross-arm  to  Pole 40 

Attaching  Braces  to  Pole 41 

[  077  ] 


Sec.  10  LINE  CONSTRUCTION 

ARTICLE 

Location  of  Cross-arms 42 

Side  Cross-arms 43 

Double  Arms 44 

Reverse  or  Buck  Arms 45 

Braces  with  Buck  Arms 46 

Pins 47 

Insulators 

Equipping 48-49 

Pole  Guying 

When  to  Use  Guys 50 

Straight  Line  Guying 51 

Terminal  Poles 52 

Long  Spans 53 

Corner  Poles 54 

Curved  Lines 55 

Poles  on  Hills 56-57 

Guy  Wire 58  to  60 

Guy  Fittings 61 

Guy  Attachments 62-63 

Stub  Guying 64 

Anchor  Guys 65 

Patented  Guy  Anchors 66 

Guy  Anchor  Protection , 67 

Locating  Foot  of  Anchor  Guv 68 

Tree  Guying ! 69  to  71 

Method  of  Fastening  Guys 72-73 

Two  Guys " 74  to  76 

Cross-arm  Guys 77 

Guy  Before  Running  Wires 78 

Clearance 79 

Iron  Poles 80 

Guy  Insulation 81 

Wire  and  Wire  Stringing 

Wire  Sizes 82 

Wire  Insulation 83 

Support  of  Wires 84 

Wires  Attached  to  Structures 85-86 

Clearance 87  to  91 

Tree  Trimming 92-94 

Running  Through  Trees 95-96 

Abrasion  Moulding 97  to  99 

Tree  Insulators 100 

Line  Sag 101-102 

Tie  Wires 103 

Splicing  Wires 104  to  106 

Taps 107 

f  678  ] 


LINE  CONSTRUCTION  Sec.  10 

ARTICLE 

Branch  Lines 108 

Spreader  Brackets 109 

Pole  Wiring 110 

Neat  Work Ill 

Line  Terminals 112 

Corners 113 

Dead  Wires 114 

Reinforcing  Wires 115 

Systems  of  Distribution 116  to  118 

Carrying  Capacity 119 

Lines  on  Private  Property 120 

Location  of  Wires 

Series  Circuits 121 

Multiple  Circuits 122 

Locations  on  Pins 123 

Temporary  Work  to  be  Avoided 124 


[  679  ] 


SPECIFICATIONS  FOR  METHODS  OF  AERIAL 
CONSTRUCTION 

1.  Scope.     These  specifications  cover  construction  methods  for 
distributing  systems  as  follows: — Mechanically,  for  spans  up  to  and 
including  130  feet;   electrically,  for  street  lighting  circuits  and  for 
constant  potential  circuits  up  to  and  including  6600  volts  between 
adjacent  wires  on  the  same  cross-arm      Higher  voltages  and  longer 
spans  may  be  used,  provided  the  spacing  between  the  wires,  the  type 
of  insulators,  sags,  etc.  are  made  consistent  with  such  work.     Rail- 
road and  wire  crossing  shall  be  made  in  accordance  with  the  joint 
crossing  specifications. 

POLES  AND  POLE  SETTING 

2.  Specification.     All  poles  shall  be  purchased  under,  and  conform 
to  the  standard  specifications  for  poles,  (Sec.  2.) 

3.  Height.     Unless    special    poles    are    required    by    municipal 
ordinance,  or  by  exceptional  conditions,  the  standard  height  of 
poles  in  cities  or  thickly  settled  localities  shall  be  35  feet  for  poles 
to  carry  either  one  or  two  cross-arms;  40  feet  for  poles  to  carry  three 
or  four  cross-arms;  and  45  feet  for  poles  to  carry  over  four  cross- 
arms.     For  lines  in  suburban  districts  30-foot  poles  may  be  used 
to  advantage,  and  their  use  is  recommended.     In  general,  stability 
of  construction  is  sacrificed  by  using  poles  higher  than  necessary. 
The  height  of  a  pole  is  always  considered  as  the  total  length  over  all. 

4.  Trimming.     Before  being  set,  poles  shall  be  well  trimmed  and 
shaved,  every  effort  being  made  to  have  their  appearance  when  set 
as  unobjectionable  as  possible. 

5.  The  top  of  each  pole  shall  be  roofed  at  an  angle  of  45  degrees, 
as  shown  in  Fig.  366. 

6.  Cross-arm  Gains.    Gains  and  bolt  holes  for  the  cross-arms  up 
to  the  expected  carrying  capacity  of  the  line  shall  be  cut  in  a  pole 
before  the  same  is  set.     Gains  shall  be  cut  square  with  the  axis  of 
the  pole  and  with  all  other  gains.     Gains  shall  be  4>£  inches  wide 
to  securely  fit  the  cross-arms  and  shall  be  Y^  inch  deep  and  spaced 
24  inches  apart  on  centers,  as  shown  in  Fig.  366. 

7.  Reverse  or  Buck-arm  Gains.     Where  reverse  or  buck-arms  are 
to  be  placed  on  a  pole,  the  cross-gains  shall  be  cut  at  right  angles 
to  the  line  gains. 

8.  Cross-arm  gains,  bolt  holes  and  pole  tops  shall  be  painted  with 
at  least  one  coat  of  preservative  paint  before  the  pole  is  set. 

9.  Painting.     Poles  that  are  to  be  painted  in  order  to  improve 
their  appearance,  shall  be  given  a  priming  coat  of  standard  green 
pole  paint  before  being  taken  from  the  yard.     After  the  pole  is  set 
and  construction  line  work  thereon  has  been  completed,  the  poles 

[  681  1 


Sec.  10 


LINE  CONSTRUCTION 


FIG.  366. — Pole  framing. 
[  682  ] 


LINE  CONSTRUCTION  Sec.  10 

shall  be  given  a  second  or  finishing  coat  of  standard  green  pole 
paint.  Cross-arm  braces,  pins,  switchboxes,  pole  steps  and  other 
fixtures,  shall  be  painted  when  this  finishing  coat  is  applied. 

10.  Pole  Numbering.     Every  pole  belonging  to  the  electric  light 
or  power  company  and  every  pole  that  is  the  joint  property  of  the 
company,  and  of  some  other  company,  should  be  numbered.     The 
designating  number  of  the  pole  shallbe  stencilled  thereon  as  soon 
as  possible  after  the  pole  has  been  set. 

11.  Rights-of-Way.     In  selecting  the  route  of  a  pole  line,  it  is 
important  to  consider  the  district  through  which  the  line  will  extend, 
as  well  as  the  probable  business  that  can  be  connected  to  such  a 
line. 

12.  Street  Rights-of-Way.     Lines  should  be  arranged  to  follow 
one  side  of  the  thoroughfare  as  much  as  possible  to  reduce  the 
number  of  crossings  to  a  minimum.     In  designing  a  new  line,  care 
should  be  taken  to  obtain  an  unobstructed  right-of-way,  selecting 
a  location  which  will  not  conflict  with  existing  pole  lines  of  other 
companies.     It  is  undesirable  to  erect  pole  lines  on  the  same  side 
of  the  street  as  existing  pole  lines. 

13.  Back  Yard  Rights-of-Way.     It  will  sometimes  be  found  desir- 
able to  locate  poles  along  the  rear  lot  lines,  but  unless  permanent 
rights-of-way  are  secured,  such  poles  shall  not  be  used  for  carrying 
important   feeders  or  mains.     Poles   carrying  feeders  and   mains 
shall  preferably  be  located  on  public  streets,  not  only  because  the 
rights-of-way  are  more  permanent,  but  also  because  poles  so  located 
are  available  for  supporting  street  lamps. 

14.  Locating  Poles  on  Street.     Efforts  should  be  made  to  select 
the  following  locations  for  poles: 

(a)  At  the  junctions  of  all  streets  or  alleys  to  facilitate  the  in- 
stallation of  branch  lines,  feeders  and  service  connections. 

(b)  Poles  in  all  cases  should  be  located  so  as  not  to  obstruct  door- 
ways, windows,  porches,  gates,  coal  holes,  runways,  etc. 

(c)  At  railroad  crossings  unless  physical  conditions  or  municipal 
requirements  prevent  the  side  clearance  should  be  not  less  than  12 
feet  from  the  nearest  track  rail  of  main  line  tracks  and  6  feet  from 
the  track  rail  of  a  siding. 

15.  Spacing.     On  straight  sections,  wood  pole  lines  for  distribu- 
tion work  shall  have  a  length  of  span  approximating  125  feet. 
On  curves  and  corners  the  spans  shall  be  shortened  as  given  in  Table 
Fig.  367. 

16.  Street  Crossings.     When  a  line  must  cross  from  one  side  of 
a  street  to  the  other,  the  crossing  shall  be  made  with  the  smallest 
possible  angle  of  deviation  in  the  line,  but  the  span  should  not  exceed 
110  feet.     The  spans  on  the  straight  lines  next  to  and  on  either  side 
of  the  crossing,  shall  also  be  shortened  from  the  standard  pole 
spacing  of  125  feet  to  100  feet  or  less. 

[  683  ] 


Sec.  10 


LINE  CONSTRUCTION 


v/) 


_ 

Db. 


i 


11! 


11 


"e3 


ill 


LINE  CONSTRUCTION 


Sec.  10 


17.  Heavy  Poles.     The  heaviest  poles  shall  be  placed  att  line 
terminals,  corners,  street  crossings  and  other  points  of  exceptional 
strain;  and  at  such  points  the  depth  of  pole  setting  shall  be  increased 
at  least  6  inches,  as  specified  in  the  table  given  in  Art.  21.     At  all 
such  points  the  length  of  adjacent  spans  shall  be  reduced  from  the 
standard  pole  spacing. 

18.  Clearing  Obstacles.     To  clear  obstacles,  such  as  buildings, 
railroad  gates,  foreign  pole  lines,  bridges,  etc.,  poles  shall  be  used 
of  sufficient  height  and  so  located  that  there  will  be  ample  clearance 
between  the  obstacle  and  the  nearest  line  wire. 

19.  Line  Level.     The  length  of  poles  shall  be  so  proportioned  to 
the  contour  of  the  country,  or  to  adjacent  poles  of  exceptional 
height  set  to  clear  obstacles,  that  abrupt  changes  in  the  level  of  the 
wires  will  not  occur. 

20.  Curb  Line.     Poles  set  along  a  curb  line  shall  be  located  so 
that  there  is  a  clear  space  of  about  6  inches  between  the  nearest 
surface  of  the  pole  and  the  outside  edge  of  the  curb.     Poles  on 
country  roads  where  the  curb  line  is  not  laid  out  should  be  set  as 
nearly  as  possible  6  inches  inside  of  the  line  which  the  curb  will 
follow,  so  that  when  the  street  is  afterwards  laid  out  and  curbed, 
the  poles  need  not  be  shifted. 

21.  Pole  Setting.     Poles  shall  be  set  in  the  ground  to  a  depth 
not  less  than  that  given  in  the  following  table. 


TABLE  110 

POLE  SETTINGS 

Depth  j 

n  Ground 

Length  Over  All 
in  Feet 

Curves,  Corners  and 

Straight  Lines 

Points  of  Extra  Strain 

30 

5.0  feet 

6.0  feet 

35 

5.5 

6.0 

40 

6.0 

6.5 

45 

6.5 

7.0 

50 

6.5 

7.0 

55 

7.0 

7.5 

60 

7.0 

7.5 

65 

7.5 

8.0 

70 

7.5 

8.0 

75 

8.0 

8.5 

80- 

8.0 

8.5 

f  685  ] 


Sec.  10 


LINE  CONSTRUCTION 


22.  All  holes  shall  be  dug  large  enough  to  admit  the  pole  without 
forcing  and  shall  have  the  same  diameter  at  the  top  as  at  the  bottom. 

23.  Poles  shall  be  set  to  stand  perpendicularly  when  the  line  is 
completed.     Exception  can  be  taken  to  this  rule,  in  that  a  very 
slight  lean  against  the  strain  can  be  given  to  poles  at  line  terminals, 
corners,  curves  and  other  points  of  excessive  strain. 

24.  Poles  with  a  bend  or  crook  shall  be  so  placed  in  a  line  that  the 
defect  is  as  unsightly  as  possible.     In  general,  this  result  will  be 
obtained  by  turning  the  pole  bend  in  the  same  direction  as  that 
followed  by  the  line. 

25.  After  a  pole  is  placed  in  position,  only  one  shovel  shall  be 
used  in  filling  the  hole,  while  three  tampers  continuously  pack  in  the 
filling  until  the  hole  is  completely  filled. 


Crib  Braces 
from  4'  to  6* 
length 


FIG.  368. — Crib  bracing. 

26.  After  the  hole  is  completely  filled,  soil  shall  be  piled  up  and 
packed  firmly  around  the  pole,  and  any  sod  which  has  been  removed 
to  set  the  pole  shall  be  neatly  replaced.     New  pole  settings  shall  be 
inspected  after  they  have  been  subjected  to  a  heavy  rainstorm,  to 
make  sure  that  the  filling  has  not  sunk  and  left  around  the  pole  a 
cavity  dangerous  to  the  public  safety. 

27.  Crib  Bracing.     Poles  which  cannot  be  strongly  guyed,  and 
which  must  be  set  in  soft  ground,  may  be  given  additional  stability 

[  686] 


LINE  CONSTRUCTION  Sec.  10 

by  crib  bracing,  as  shown  in  Fig.  368.  This  consists  of  placing  at 
the  point  of  maximum  strain  two  logs,  about  five  feet  long  and  not 
less  than  8  inches  in  diameter.  The  top  brace  alone,  or  both 
braces,  can  be  used  according  to  the  amount  of  additional  stability 
required. 

28.  Artificial  Foundation.     When  exceptional  stability  is  required 
of  a  pole  setting,  an  artificial  foundation  of  concrete  may  be  placed 
around  the  base  of  the  pole.     This  concrete  filling  shall  extend  at 
least  one  foot  from  the  pole  on  all  sides,  be  carried  above  the  ground 
line  and  bevelled  to  shed  water,  and  shall  consist  of  one  part  Port- 
land cement,  three  parts  sand  and  six  parts  broken  stone  or  clean 
gravel,  and  mixed  wet. 

29.  Quicksand.     When  poles  are  to  be  set  in  quicksand  or  in 
soft,  muddy  soil,  where  the  digging  is  difficult  and  the  setting  in- 
secure, the  following  method  shall  be  used:  As  soon  as  a  hole  reaches 
a  depth  where  the  sides  are  continually  caving  in,  place  a  barrel, 
without  top  or  bottom,  in  the  hole,  digging  down  from  inside  of 
same,  and  driving  down  the  barrel  as  the  hole  progresses.     When 
the  required  depth  has  been  reached,  set  the  butt  of  the  pole  in 
the  barrel,  filling  the  latter  with  concrete  and  rock,  as  specified 
above  for  artificial  foundation.     If  much  of  this  work  is  encountered, 
the  use  of  a  special  sheet-iron  barrel  constructed  in  two  parts,  so 
that  the  same  can  be  moved  from  hole  to  hole,  will  expedite  the  work. 

30.  Poles  Located  in  Rock.     When  poles  are  set  in  rock,  the  depth 
of  setting  may  be  decreased,  depending  upon  the  character  of  the 
rock. 

31.  Protection.     Where  the  use  of  wood  poles  as  hitching  posts 
for  horses  cannot  be  avoided,  the  pole  shall  be  protected  by  a  sub- 
stantial metal  covering.     Where  poles  are  so  placed  as  likely  to  be 
damaged  by  wagon  wheels,  they  should  be  protected  with  hub  guards. 

POLE  STEPS 

32.  Poles  to  be  Stepped.     All  poles  carrying  branch  cutouts, 
incandescent  lamps  or  other  attachments  that  may  require  frequent 
attention,  as  also  all  testing  poles,  shall  be  stepped  to  facilitate 
climbing  the  same.     For  the  same  reason  it  will  be  found  convenient 
to  step  poles  carrying  transformers. 

33.  Galvanized  Iron  Pole  Steps.     To  fit  steps  to  a  pole,  bore 
|^-inch  holes  4  inches  into  the  pole  in  locations  as  hereinafter  speci- 
fied, and  drive  steps  into  these  holes  until  they  project  only  6  inches 
from  the  pole,  then  with  a  wrench  turn  the  steps  so  that  the  foot 
guard  points  upward. 

34.  Location  on  Pole.     The  location  of  pole  steps  on  a  pole  is 
shown  in  Fig.  369.     The  lowest  step  shall  be  7  feet  4  inches  from 
the  ground.     It  will  be  necessary  to  bore  the  pole  with  additional 
holes  for  steps  at  the  locations  specified  in  Fig.  369,  so  that  linemen 

[  687  ] 


Sec.  10 


LINE  CONSTRUCTION 


FIG.  369. — Location  of  steps  on  pole. 
[  688  ] 


LINE  CONSTRUCTION 


Sec.  10 


SOCKET 


SOCKET 


iiK 


:O 


STEP 


FIG.  370. — Two  types  of  pole  step  sockets. 
[  689  ] 


Sec.  10  LINE  CONSTRUCTION 

can  insert  small  iron  bolts  or  other  form  of  portable  pole  steps  when 
climbing  the  pole.  These  holes  shall  be  equipped  with  pole-step 
sockets,  as  shown  in  Fig.  370. 

35.  Pole  steps  shall  always  be  placed  on  a  line  with  the  street  in 
which  the  pole  is  located. 

CROSS-ARMS 

36.  Cross-arms.   Owing  to  the  variations  in  dimensions  and  pin 
spacings  of  cross-arms  now  in  use,  it  is  difficult  to  specify  crossarrns 
that  will  suitably  conform  to,  or  completely  cover,  present  practice. 
Whatever  arm  is  used  the  spacing  between  the  pole  pins  shall  not 
be  less  than  20  inches,  nor  should  the  spacing  between  the  side 
pins  be  less  than  10^  inches.     The  arms  covered  by  specification 
contained  in  Sec.  4,  Art.  2,  are  recommended  as  satisfactory  standards. 

37.  Size  Arms  to  Use.     It  is  recommended  that  the  six-pin  arm 
be  adopted  for  general  use.     The  four-pin  arm  shall  only  be  used 
for   single-arm   suburban   lines   and   for   service   buck    arms.     An 
eight-pin  arm  may  be  used  for  heavy  pole  lines,  especially  by  com- 
panies having  systems  requiring  four-wire  distribution. 

38.  Painting  and  Treating.     Cross-arms  shall  be  seasoned  for  at 
least  three  months,  and  if  not  to  receive  a  preservative  treatment, 
shall  be  painted  with  two  coats  of  standard  white  lead  paint  before 
leaving  the  yard.     The  use  of  cross-arms  which  have  been  properly 
treated   with   a   suitable   preservative   is   recommended,    and    the 
treatment  should  be  as  provided  for  in  the  specifications  of  the 
National  Electric  Light  Association   Committee   on   Preservative 
Treatment  of  Wood  Poles  and  Cross-arms,  (Sec.  9,  Part  II.) 

39.  Cross-arm  Bracing.     Before  being  placed  on   a  pole,    each 
cross-arm  shall  be  fitted  with  two  braces,  the  braces  shall  be  attached 
to  the  front  of  the  cross-arm  by  carriage  bolts,  which  shall  pass  first 
through  a  washer,  then  through  the  cross-arm  and  then  through  the 
brace  with  the  nut  on  the  brace  side. 

40.  Fitting  Cross-arm  to  Pole.     When  possible,  cross-arms  shall 
be  fastened  to  a  pole  before  the  latter  is  set.     Each  cross-arm  shall 
be  attached  to  the  pole  by  one  f^-inch  cross-arm  bolt,  driven  through 
from  the  back  of  the  pole.     This  cross-arm  bolt  shall  be  of  sufficient 
length  to  pass  completely  through  the  pole  and  the  cross-arm,  and 
receive  its  complement  of  washers  and  nuts.     One  washer  shall  be 
placed  under  the  head  and  one  under  the  nut  at  the  end  of  the  bolt . 
Cross-arm  bolts  of  a  proper  length  for  the  thickness  of  the  pole  shall 
be  used.     The  back  of  the  pole  shall  never  be  cut  out  to  allow  the 
use  of  a  shorter  bolt,  and  projecting  ends  are  not  to  be  left  on. 

41.  Attaching  Braces  to  Pole.    Each  pair  of  cross-arm  braces 
shall  be  attached  to  the  pole  by  means  of  one  SJ^-inch  lag  bolt. 

[  690  ] 


LINE  CONSTRUCTION 


Sec.  10 


42.  Location  of  Cross-arms.  Cross-arms  shall  invariably  be 
placed  either  at  right  angles  or  parallel  to  the  line  of  the  street  on 
which  the  pole  is  set.  They  shall  always  be  faced  on  the  opposite 
side  of  the  pole  from  that  on  which  the  maximum  strain  comes. 
On  straight  lines  where  the  spans  between  poles  are  equal  the  cross- 
arms  shall  be  faced  alternately  on  succeeding  poles,  first  in  one 
direction  and  then  in  the  other. 


f  Through  Bolt 
--Vertical  Brace 


FIG.  371. — Side  cross-arm  bracing. 

43.  Side  Cross-arms.  It  is  sometimes  necessary,  in  order  to  avoid 
obstructions,  to  use  a  side  or  offset  arm.  In  such  cases,  a  special 
arm  of  the  same  dimensions  as  the  standard  arm  shall  be  used. 
This  arm  shall  be  bored  for  pins  and  bolt  holes  and  installed  with 
angle  iron  brace  and  back  brace,  as  shown  in  Fig.  371.  If  the  pole 
carries  a  heavy  line,  the  unbalanced  strain  should  be  counteracted 
by  side-guying  or  by  ground  braces,  if  the  installation  of  side  guys 
is  impracticable. 

[  691] 


Sec.  10 


LINE  CONSTRUCTION 


44.  Double  Arms.  At  line  terminals,  corners,  curves,  where  the 
line  crosses  over  from  one  side  of  the  street  to  the  other  and  at 
points  where  there  is  an  excessive  or  unbalanced  strain  on  the  cross- 
arms,  pins  and  insulators,  the  pole  should  be  doubled  armed  as 
illustrated  in  Fig.  372.  Two  blocks  equal  in  length  to  the  thick- 
ness of  the  pole  between  gains  shall  be  placed  between  the  arms, 


one  at  each  end  between  the  two  outside  pins.  An  y^-inch  hole 
shall  be  bored  at  this  point  through  the  cross-arms  and  the  inter- 
vening block.  The  two  cross-arms  shall  then  be  bolted  together 
by  two  5^-inch  bolts  of  proper  length,  passing  through  the  cross-arms 
and  the  blocks,  a  washer  being  placed  at  both  ends  of  each  bolt. 

[692] 


LINE  CONSTRUCTION 


Sec.  10 


In  place  of  the  wooden  blocks,  described  above,  spreader  bolts 
may  be  used,  as  shown  in  Fig.  373.  When  a  cross-arm  guy  is  to  be 
attached  to  the  arm,  an  eye  bolt  may  be  substituted  for  the  cross- 
arm  bolt. 

At  line  terminals  the  last  pole  shall  be  double-armed  as  specified, 
and  the  cross-arms  of  the  last  two  poles  before  the  terminal  pole 


faced  toward  the  latter.     All  poles  on  which  two  or  more  wires  are 
dead  ended  shall  be  double-armed. 

45.  Reverse  or  Buck  Arms.  At  corners,  and  where  more  than 
two  wires  branch  from  the  main  line,  buck  arms  shall  be  used. 
A  buck  arm  is  a  regulation  cross-arm  with  fittings  complete,  set  at 

[  693  J 


Sec.  10 


LINE  CONSTRUCTION 


right  angles  to  the  line  cross-arm,  and  12  inches  below  it  on  centers, 
as  previously  specified  for  buck-arm  gains.  Judgment  must  be 
exercised  in  the  use  of  buck  arms,  and  ample  room  must  be  left  for 


Guy 


n.  B 

M 

a 

0 

JUb  

V 

it 

i 

a/lnf                 HeoZGuy^ 

=3 

Li? 
p 

1  = 

C= 

»                Head  Guy 

«*  o 

y 

M 

a 

V 

Dead  End 
on  this  Pole 

Nofe:  Space  A  should 
not  be  less  them  £0"squdn& 

• 

/U 

Branch  Line 

Note;  If  impossible  to  install 
Anchor  Guy  on  Pole  3,~ 
uy  Ho  2  &2tx)3 


FIG.  374. — Junction  pole  without  double  arms. 

climbing  and  working  on  the  pole.  In  all  buck-arm  construction 
there  shall  be  one  clear  space  (neglecting  the  pole  area)  adjacent 
to  the  pole  of  at  least  20  inches  square.  (Fig.  374.) 

[  694] 


LINE  CONSTRUCTION  Sec.  10 

46.  Braces  with  Buck  Arms.    On  poles  equipped  with  buck  arms, 
the  cross-arm  braces  shall  be  so  attached  to  both  the  line  arms  and 
the  buck  arms  as  to  permit  their  installation  without  interfering 
with  the  arms  below.     This  can  be  accomplished  by  using  a  standard 
28-inch  brace,  and  attaching  the  same  to  the  cross-arms  at  23  H 
inches  from  the  center  of  the  arm,  instead  of  19  inches,  which  is  the 
standard  distance.     The  bolt  holes  in  the  arms  for  these  braces 
will  be  special,  and  shall  be  bored  in  the  field. 

47.  Pins.     Before  being  taken  from  the  yard,  each  cross-arm  shall 
be  fitted  complete  with  pins.     Pins  shall  fit  tight  into  the  holes  in 
a  cross-ai  m,  and  shall  stand  perpendicular  to  the  cross-arm  when 
fitted.     Wooden  pins  shall  be  nailed  to  the  cross-arm  with  one  six- 
penny nail  driven  straight  from  the  middle  of  the  side  of  the  cross- 
arm. 

INSULATORS 

48.  Equipping.     Insulators  shall  be  placed  upon  the  cross-arrn 
pins  only  when  the  wire  is  to  be  immediately  attached  thereto,  and 
shall  be  screwed  up  'tightly  in  every  case. 

49.  If  a  wire  be  permanently  removed  from  an  insulator,  and  no 
other  is  to  take  its  place,  the  insulator  shall  also  be  removed. 

POLE  GUYING 

50.  When  to  Use  Guys.     Guys  shall  be  used  whenever  they  can 
be  located,  so  as  to  counteract  the  strain  of  the  wires  attached  to 
the  pole  and  so  prevent  the  same  from  being  pulled  from  its  proper 
position  in  the  line.     The  following  general  instructions  cover  some 
of  the  special  cases  where  guying  is  required. 

51.  Straight-Line  Guying.     Straight-line  guying  is  for  the  purpose 
of  giving  additional  stability  to  a  line  in  case  of  severe  storms. 
On  pole  lines  carrying  more  than  one  cross-arm  it  is  desirable  to 
install  guys  on  straight-line  sections  at  approximately  every  twen- 
tieth pole.     These  storm  guys  shall  consist  of  head  guys  extending 
from  the  top  of  the  pole  to  the  adjacent  poles  in  the  line  on  either 
side,  and  if  possible,  this  same  pole  shall  be  side-guyed;    that  is, 
guys  should  extend  from  the  top  of  the  pole  on  either  side  at  right 
angles  to  the  line  to  guy  stubs  or  other  supports. 

52.  Terminal  Poles.     Line  terminal  poles  should  be  head-guyed 
against  the  strain  of  the  line  and  on  heavy  lines ;  that  is,  lines  having 
three  arms  or  more,  the  two  poles  next  to  the  terminal  pole  shall  be 
head-guyed  in  the  same  direction  to  assist  the  latter  in  taking  the 
terminal  strain. 

53.  Long  Spans.     In  the  case  of  exceptionally  long  spans,  that 
is,  spans  exceeding  150  feet  in  length,  the  next  adjacent  poles  on 
either  side  of  the  poles  supporting  the  span  shall  be  head-guyed 
against  the  strain,  as  shown  in  Fig.  375. 

[695] 


Sec.  10 


LINE  CONSTRUCTION 


[  696] 


LINE  CONSTRUCTION 


Sec.  10 


54.  Corner  Poles.  All  corner  poles,  whether  the  turn  is  made 
on  one  pole  or  on  two  poles,  shall  be  head-  and  side-guyed,  as  shown 
in  Fig.  376. 


55.  Curved  Lines.  On  curved  lines,  side  guys  shall  be  installed 
in  line  with  the  radius  of  the  curve,  and  the  pole  spacing  shall,  if 
possible,  be  reduced.  A  convenient  table  for  the  location  of  side 
guys  and  for  the  spacing  of  poles  on  curves  will  be  found  in  Fig.  367. 
In  this  table  the  word  "pull"  is  a  convenient  expression  for  describing 

[  697  ] 


Sec.  10 


LINE  CONSTRUCTION 


[  G98] 


LINE  CONSTRUCTION 

v  \'  \\ 


Sec,  10 


[  699  ] 


Sec.  10 


LINE  CONSTRUCTION 


[700] 


LINE  CONSTRUCTION  Sec.  10 

the  angle  of  deviation  which  the  line  makes  at  the  pole,  the  amount 
of  the  pull  being  the  distance  from  the  pole  to  the  straight  line 
joining  points  on  the  line  located  100  feet  each  side  of  the  pole. 
All  poles  carrying  two  crossarms  shall  be  side-guyed  where  the  pull 
exceeds  five  feet.  All  poles  carrying  one  crossarm  shall  be  side- 
guyed  where  the  pull  exceeds  ten  feet. 

56.  Poles  on  Hills.     Poles  on  steep  hills  shall  be  head-guyed  to 
take  the  down-hill  strain  of  the  line  on  the  poles. 

57.  Details  of  head-  and  side-guying  are  shown  in  Figs.  377,  378 
and  379. 

58.  Guy  Wire.     The  material  used  for  guying  shall  be  stranded 
cable,  composed  of  galvanized  steel  wire  in  accordance  with  National 
Electric  Light  Association  standard  specifications.     (Sec.  3.) 

59.  2300-pound  cable  may  be  used  for  guying  light  lines;    that 
is,  for  pole  Lines  having  not  more  than  one  crossarm  and  for  guying 
crossarms 

60.  5000-pound  cable  shall  be  used  for  all  regular  pole  guying. 

61.  Guy  Fitting.     In  connection  with  stranded  guy  cable,  gal- 
vanized iron  guy  clamps  and  thimbles  shall  be  used. 

62.  Guy  Attachments.     All  guy  wires  shall  preferably  be  attached 
to  poles,  guy  stubs,  trees  or  other  ungrounded  supports,  and  when 
so  attached  shall  not  reach  within  eight  feet  of  the  ground.     The 
reason  for  preferably  attaching  wires  to  ungrounded  supports  is 
for  the  purpose  of  insulating  guys  as  thoroughly  as  possible  from 
the  ground,  this  protection  being  in  addition  to  the  insertion  of 
strain  insulators  in  the  guy  itself  and  having  in  view  the  protection 
of  linemen  working  on  a  guyed  pole  from  coming  in  contact  with  a 
grounded  wire  when  working  on  live  wires.     It  is  also  considered 
desirable  to  keep  guys,  where  possible,  at  least  eight  feet  from  the 
ground,  with  the  idea  of  keeping  them  out  of  reach  of  persons  on 
the  highway. 

63.  There  will,  however,  be  many  cases  in  which  it  will  be  necessary 
to  install  guys  where  the  conditions  stated  in  Art.  62  cannot  be 
complied  with.     In  such  cases,  the  guy  wires  may  be  attached  to 
rocks,  stone  foundations,  iron  structures  or  other  grounded  supports, 
or  anchor  guys  may  be  installed. 

64.  Stub  Guying.     When  a  line  cannot  be  guyed  by  means  of 
other  poles  in  the  vicinity,  guy  stubs  may  be  set  as  shown  in  Figs. 
380  and  381.     Guy  stubs  shall  be  of  wood  and  shall  conform  to  the 
specifications  covering  the  line  poles.     They  shall  be  of  sufficient 
length  to  insure  the  guys  attached  to  them  clearing  roadways  by 
not  less  than  eighteen  (18)  feet,  and  footways  by  not  less  than 
twelve  (12)  feet,  and  also  to  insure  that  the  guys  attached  to  them 
shall  clear  electric  wires  by  at  least  three  feet,  as  specified  in  Art.  79. 

[701] 


Sec.  10 


LINE  CONSTRUCTION 


[702] 


LINE  CONSTRUCTION 


Sec.  10 


703  ] 


Sec.  10 


LINE  CONSTRUCTION 


65.  Anchor  Guys.  An  anchor  guy  may  be  employed  to  guy 
poles,  but  must  not  be  installed  where  it  might  interfere  with  surface 
traffic.  It  shall  be  constructed  as  shown  in  Fig.  382  and  383.  This 
anchor  shall  be  set  in  the  ground  so  that  the  eye  of  the  guy  rod  will 


3"S<juareWflsher 

FIG.  382. — Anchor  guy. 

stand  about  one  foot  above  the  ground,  the  guy  rod  being  in  line 
with  the  guy  wire  attached  thereto. 

66.  Patented  Guy  Anchors.  As  another  method  of  ^  attaching 
anchor  guys,  self-holding  anchor  rods  may  be  used,  of  which  several 
desirable  forms  are  on  the  market.  This  method  will  be  found 

[704] 


LINE  CONSTRUCTION 


Sec.  10 


[705] 


Sec.  10  LINE  CONSTRUCTION 

desirable  in  many  places,  particularly  where  the  soil  is  of  a  sandy 
or  loamy  character. 

67.  Guy-Anchor  Protection.     Anchor  guy  wires  that  are  so  close 
to  the  street  as  to  offer  in  any  way  an  obstruction  to  traffic,  should 
be  protected  with  an  anchor  shield.     This  shield  may  consist  of  a 
2^-inch  or  3-inch  pipe,  installed  as  shown  in  Fig.  381.     The  anchor 
shield  shall  extend  from  the  ground  to  a  height  of  about  eight  feet. 

68.  Locating  Foot  of  Anchor  Guy.     The  guy  anchor  shall  be  so 
located  that  the  angle  between  the  guy  and  the  pole  shall  be  approx- 
imately 45  degrees,  and  in  no  case  shall  the  distance  from  the  foot 
of  the  pole  to  the  foot  of  the  guy  be  less  than  one-fourth  of  the  height 
from  the  ground  to  the  point  of  attachment  of  the  guy  on  the  pole. 

69.  Tree  Guying.     When  guys  cannot  be  conveniently  attached 
to  pole  or  guy  stubs,  trees  may  be  used.     Guy  wires  shall  not  be 
attached  to  trees  without  permission  of  the  owner  or  other  proper 
authorities. 

70.  Tree  guys  shall  preferably  be  attached  to  tree  trunks.     When 
this  is  impossible,  attachment  may  be  made  to  a  live,  sound  limb, 
close  to  the  tree  trunk,  provided  that  the  limb  is  not  less  than  eight 
inches  in  diameter.     In  no  case  shall  a  guy  be  attached  to  a  tree  at 
a  point  where  the  swaying  of  the  tree  would  affect  the  stability  of 
the  guyed  pole. 

71.  Tree  trunks  and  limbs  shall  always  be  protected  from  injury 
by  the  use  of  tree  blocks  between  the  tree  and  the  wire  attached 
thereto.     Tree  blocks  shall  be  of  chestnut  and  shall  be  placed  around 
a  tree  trunk  or  limb  sufficiently  close  together  to  prevent  the  wire 
from  touching  the  same.     To  avoid  injury  to  the  tree,  guy  wires 
shall  not  be  wrapped   continuously  around  the  same,  but  shall 
simply  pass  around  the  tree,  supported  on  blocks,  as  shown  in 
Figs.  384  and  385.     To  hold  the  blocks  in  place  while  the  guy  is 
being  attached,  a  winding  tape,  or  rope,  is  sometimes  convenient. 

72.  Method  of  Fastening  Guys.     Guy  wires  shall  be  attached  to 
poles  and  stubs  by  making  two  complete  turns  of  the  wire  about  the 
pole.     The  end  of  the  wire  shall  then  be  clamped  to  the  guy  and  the 
projecting  end  fastened  thereto  by  a  wrapping  of  galvanized  iron 
wire,  as  shown  in  Fig.  386. 

73.  Where  a  pole  has  one  or  two  crossarms,  the  guy  shall  be 
attached  directly  below  the  top  crossarm,  as  shown  in  Fig.  380. 

74.  Two  Guys.     Where  the  pole  has  three  or  more  crossarms, 
two  guys  may  be  attached,  one  directly  below  the  top  crossarm  and 
the  other  directly  below  the  third  crossarm,  as  shown  in  Fig.  380. 

75.  When  two  or  more  guy  wires  run  to  a  pole  or  guy  stub  in 
close  proximity  to  each  other,  the  attachment  of  one  guy  shall 
never  over  lap  that  of  another,  but  shall  be  entirely  independent 
thereof. 

[  706  ] 


LINE  CONSTRUCTION 


Sec.  10 


FIG.  384. — Guying  to  trees  or  iron  poles. 


FIG.  385.— Standard  tree  block. 
[707] 


Sec.  10 


LINE  CONSTRUCTION 


\, 


[  708  ] 


LINE  CONSTRUCTION  Sec.  10 

76.  When  a  pole  is  guyed  with  two  or  more  guys  pulling  in  approx- 
imately the  same  direction,  a  turnbuckle  shall  be  installed  in  each 
guy  to  enable  the  strain  to  be  equalized. 

77.  Cross-arm  Guys.     Wires  must  sometimes  be  attached  to  a 
cross-arm  so  that  there  is  an  unbalanced  strain  on  one  side  of  the 
arm,  tending  to  twist  it  out  of  position  on  the  pole.     In  such  cases, 
the  cross-arm  shall  be  held  in  position  by  attaching  the  guy  wire 
thereto,  but  it  is  advisable  to  limit,  so  far  as  possible,  the  use  of 
cross-arm  guys.     Cross-arm  guys  shall,  as  a  rule,  extend  back  to 
the  guy  post  independently  of  each  other  or  of  pole  guys,  as  shown 
in  Fig.  387.     On  light  lines,  however,  it  is  sometimes  advisable  to 
combine  two  guys  into  one  "Y"  or  bridle  guy. 

78.  Guy  Before  Running  Wires.     In  new  construction  work  and 
in  rebuilding  old  lines,  guy  wires  shall  be  placed  at  points  of  excessive 
strain  and  the  poles  held  in  proper  position  before  the  lines  are 
strung. 

79.  Clearance.     Guys  shall  be  attached  to  poles  so  as  to  interfere 
as  little  as  possible  with  workmen  climbing  or  working  thereon. 
Every  guy  which  passes  either  over  or  under  any  electric  wires  other 
than  those  attached  to  the  guyed  pole,  shall  be  so  placed  and  main- 
tained as  to  provide  a  clearance  of  not  less  than  three  feet  between 
the  guy  and  such  electric  wires.     As  changes  in  temperature  will 
effect  the  sag  of  the  wires  more  than  that  of  the  guy,  the  latter  being 
under  strain,  allowance  must  be  made  therefore  at  the  time  the  guy 
is  installed.     For  clearance  of  guys  above  ground,  see  Arts.  62  and  64. 

80.  Iron  Poles.     When  it  is  necessary  to  attach  a  guy  to  an  iron 
pole,  tree  blocks  shall  always  be  used  between  the  iron  pole  and  the 
guy  wire  to  insulate  the  latter  from  the  grounded  iron  pole,  as  shown 
in  Fig.  384. 

81.  Guy  Insulation.     All  guy  wires  attached  to  poles  carrying 
electric  light  or  power  wires  shall  be  insulated  by  the  insertion  of 
two  strain  insulators,  the  upper  of  these  insulators  being  inserted 
in  the  guy  so  as  to  be  at  least  six  feet,  in  a  horizontal  direction, 
from  the  pole  itself,  or  at  least  six  feet  below  the  lowest  line  wire, 
and  the  second  strain  insulator  shall  be  inserted  in  the  guy  so  as  to 
be  between  six  feet  and  eight  feet  from  the  lower  end  of  the  guy 
and  at  least  eight  feet  from  the  ground.     In  short  guys  in  which 
the  two  insulators  here  required  would  be  located  at  the  same 
point  or  near  each  other,  the  two  insulators  may  be  coupled  in  series 
and  put  into  the  guy  together. 

WIRE  AND  WIRE  STRINGING 

82.  Wire  Sizes.     For  mains  or  feeders,  wires  shall  be  of  copper, 
aluminum  or  copper  covered  steel,  and  no  wire  having  a  breaking 
strength  less  than  No.  6  soft  drawn  copper  shall  be  used.     For 
service  connections,  No.  8  B.  &  S.  gauge  soft  drawn  copper  wire 
may  be  used  in  spans  up  to  and  including  80  feet  in  length. 

[709] 


Sec.  10 


LINE  CONSTRUCTION 


Note:  Head  Guy  from 
Poles  I  &2  to  foot  of 
Junction  Pole. 


FIG.  387. — Cross-arm  guying.     One-pole  method  of  turning  corner. 
[  710  ] 


LINE  CONSTRUCTION  Sec.  10 

Up  to  and  including  No.  00  B.  &  S.  Gauge  solid  or  stranded  wire 
may  be  used.  Stranded  cable  shall  be  used  for  all  wire  sizes  larger 
than  No.  00  B.  &  S.  gauge.  This  rule  does  not  necessarily  apply 
to  500  volt  trolley  feeders. 

Larger  solid  wires  than  No.  00  have  sufficient  strength,  but  are 
more  difficult  to  handle  and  erect  and  therefore  undesirable. 

83.  Wire  Insulation.     The  standard  insulation  for  line  wires  shall 
be  a  triple-braided,  weatherproof  covering. 

84.  Support  of  Wires.     Line  wire  shall  be  carried  upon  standard 
insulators  upon   crossarms    attached  to  poles.     They  shall  not  be 
carried  on  wooden  bracket  pins.     Secondary  wires  may  be  carried 
on  iron  or  steel  secondary  racks,  when  such  racks  are  securely 
through-bolted  to  the  pole. 

85.  Wires  Attached  to  Structures.     Primary  or  secondary  wires 
shall  not  be  supported  upon  trees.     Primary  lines  shall  not  be 
attached  to  buildings  if  pole  construction  with  proper  clearance 
is  practicable,  but  when  absolutely  necessary,  primary  wires  may  be 
attached  to  buildings  by  means  of  special  construction.     In  design- 
ing this  structure,  ample  clearance  should  be  provided  between  the 
nearest  primary  wire  and  any  projecting  parts  of  the  building, 
windows  or  fire  escapes. 

When  primary  wires  must  be  carried  into  buildings  other  than 
central  stations  or  sub-stations,  connections  should  generally  be 
made  by  means  of  cable  running  through-conduits. 

86.  When  a  high  potential  series  circuit  must  be  attached  to  a 
building  in  order  to  supply  commercial  series  arc  lighting  therein, 
the  wires  must  be  installed  in  such  a  way  as  to  be  beyond  the 
possibility  of  accidental  contact  by  people  in  or  about  the  place, 
and  also  so  as  to  avoid  possibility  of  contact  with  awnings,  shutters, 
signs  and  similar  fixtures  on  the  building. 

87.  Clearance.     The  clear  space  between  the  crown  of  the  road 
and  wires  crossing  the  same  shall  always  conform  to  municipal 
ordinances  or  rules,  but  in  no  case  shall  such  clear  space  be  less  than 
twenty-one  feet.     Similarly,  the  clear  space  between  sidewalks  and 
wires   crossing  them  shall  never  be  less  than  fifteen  feet.     The 
clearance  over  railroad  crossings  shall  be  30  feet.  • 

88.  All  guys  crossing  a  roadway  or  footway  shall  be  carried  at 
an  elevation  of  not  less  than  eighteen  feet  above  the  crown  of  the 
roadway  and  not  less  than  twelve  feet  above  the  footway. 

89.  The  perpendicular  distance  between  wires  when  attached  to 
the  same  supporting  structure  should  not  be  less  than  the  standard 
spacing  of  the  cross-arm  gains,  except  where  rigidly  attached  to  the 
poles  as  when  buck-arms  or  spreader  brackets  are  used. 

The  perpendicular  distance  or  clearance  between  secondary  wires 
attached  to  the  same  pole  line,  where  a  vertical  distribution  system 
is  used,  may  be  materially  decreased. 

[711] 


Sec.  10 


LINE  CONSTRUCTION 


90.  The  perpendicular  distance  between  wires  crossing  in  the 
span  shall  be  four  feet. 

91.  Line  wires  shall  clear  all  roofs  so  that  they  cannot  be  reached 
from  the  same,  and  they  shall  be  so  run  that  they  cannot  be  readily 
reached  from  any  portion  of  any  other  building  or  structure.     If 
conditions  require  that  they  be  attached  to  structures,  as  for  example, 
in  running  under  railroad  or  highway  bridges,  they  shall  be  protected 
with  sufficient  insulation  for  the  voltage  carried,  for  the  entire  distance, 


FIG.  388. — Abrasion  moulding. 

where  attached  to  the  structure,  and  to  a  point  on  either  side  of  the 
structure  that  will  be  beyond  the  reach  of  anyone  working  thereon. 

92.  Tree  Trimming.  It  is  essential  for  the  safe  and  uninterrupted 
operation  of  lines  that  they  be  free  from  possibility  of  grounding 
on  trees.  It  is,  therefore,  important  that  tree  branches  interfering, 

[712] 


LINE  CONSTRUCTION  Sec.  10 

or  likely  to  interfere,  with  the  lines  should  be  cut  away.  Such 
trimming  must  be  done  with  care  and  judgment  and  under  the 
immediate  supervision  of  the  superintendent,  line  foreman  or  other 
responsible  person. 

93.  Before  any  trimming  is  done,  the  consent  of  the  owner  of 
the  tree  should  be  obtained.     Opposition  to  tree  trimming  may 
sometimes  be  overcome  by  offering  to  employ  a  professional  gardener 
for  this  purpose.     If  consent  to  trim  trees  cannot  be  obtained,  and 
the  interfering  branches  cannot  be  avoided  by  the  use  of  longer 
crossarms  or  by  offsetting  the  standard  crossarms,  tree  wire  shall  be 
used,  as  specified  in  Art.  95. 

94.  Trees  can  generally  be  best  trimmed  in  the  Fall  and  Winter 
months  when  the  leaves  are  off  and  the  result  of  the  work  will  be 
less  noticeable.     When  branches  have  been  cut  off,  they  shall  not 
be  left  to  litter  the  streets,  nor  thrown  into  the  nearest  vacant  lot, 
but  shall  be  removed.     The  stubs  of  branches  shall  always  be 
painted  for  their  protection  and  to  make  them  less  noticeable. 

95.  Running  Through  Trees.     When  lines  must  be  carried  through  * 
trees  that  cannot  be  cleared  or  trimmed  so  as  to  give  a  clear  passage 
for  the  wires,  tree  wire  shall  be  used. 

96.  Sections  of  this  approved  tree  wire  shall  be  cut  into  the  line, 
when  running  through  trees.     Weatherproof  wire  shall  be  used  in 
those  portions  of  the  line  clear  of  trees. 

97.  Abrasion  Moulding.     Where  tree  wire  is  used,  if  there  is 
danger  of  limbs  or  large  branches  chafing  the  insulation,  it  shall  be 
protected  by  means  of  wooden  abrasion  moulding.     A  satisfactory 
form  of  wood  moulding  is  shown  in  detail  in  Fig.  388. 

98.  Before  being  placed  on  the  line,  the  moulding  shall  be  treated 
with  one  coat  of  P.  &  B.  paint  to  increase  the  insulating  qualities 
in  the  wood,  the  same  being  thoroughly  dried  before  the  moulding 
is  used.     The  moulding  shall  be  attached  at  its  ends  to  the  wires, 
as  shown  in  Fig.  388,  by  three  tight  wraps  of  No.  12  copper  wire 
around  the  moulding,  and  by  similar  wraps  at  intervals  of  not  more 
than  eighteen  inches,  if  the  strip  is  more  than  two  feet  long.     The 
abrasion  moulding  shall  be  cut  sufficiently  long  to  avoid  any  chance 
of  tree  limbs  ever  catching  under  the  end  of  same  and  ripping  it 
off  the  wire  or  sliding  it  out  of  place.     To  fasten  the  moulding  at 
the  proper  place  on  the  line,  wind  tape  tightly  at  each  end,  as  shown 
in  Fig.  388. 

99.  Wood  abrasion  moulding  shall  not  be  used  on  weather-proof 
wire  carrying  over  600  volts. 

100.  Tree  Insulators.     In  some  cases  it  will  be  found  convenient, 
where  wires  are  carried  through  trees,  to  use  special  tree  insulators. 
The  insulators  used  for  this  purpose  shall  be  of  a  type  that  will 
hold  the  wires  away  from  the  limbs  of  the  trees,  but  without  re- 

[  713  ] 


Sec.  10 


LINE  CONSTRUCTION 


quiring  that  the  wires  should  be  rigidly  attached  to  the  insulators, 
the  object  being  that  there  shall  be  sufficient  play  of  the  wire  in  the 
insulator  to  permit  the  swaying  of  the  trees. 

101.  Line  Sag.  It  is  suggested  that  when  pulling  up  lines  by 
means  of  jack-straps,  blocks  and  tackle,  or  other  devices,  the 
following  sag  or  dip  be  allowed  in  a  line  of  soft  drawn  copper  wire: 


TABLE   111 
DIP  IN  ANNEALED  COPPER  LINE  WIRE 

Span  in  Feet. 

DEFLECTION  IX  INCHES. 

Temperature 

n  Degrees  Fahrenheit. 

20 

40 

GO 

70 

80 

100 

120 

60 
70 
80 
90 
100 
110 
120 
130 

4 
6 
7 
10 
14 
18 
22 
27 

5 
7 
10 
13 
16 
21 
25 
30 

6 
9 
12 
15 
19 
23 
27 
32 

7 
10 
13 
16 
20 
24 
28 
33 

11 
14 
17 
21 
25 
30 
35 

9 
12 
15 
19 
23 
27 
32 
37 

11 
14 
17 
21 
25 
29 
34 
39 

102.  In  running  line  wires,  the  wire  shall  be  paid  out  from  the 
coil  by  revolving  the  latter,  in  order  to  avoid  twisting  the  wire. 
For  this  reason,  wire  coiled  without  reels  shall  be  placed  upon  reels 
before  being  unwound. 

103.  Tie  Wires.     All  tie  wires  shall  have  a  surface  of  the  same 
metal  as  that  of  the  line  wire  in  order  to  prevent  corrosion. 

They  shall  be  dead  soft  so  that  when  twisted  up  they  will  hold 
tight  and  not  tend  to  spring  loose.  They  must  be  strong  enough 
to  hold  the  line  wire  securely  to  the  insulator. 

On  straight  lines,  all  wires  shall  be  tied  on  the  pole  side  of  the 
insulators  with  the  exception  of  the  wires  on  the  pole  pins,  which 
shall  be  tied  on  the  side  of  the  insulator  away  from  the  pole  as  shown 
in  Fig.  389.  On  straight  line  work  the  top  groove  of  top  groove 
insulators  may  be  used  instead.  On  curves  and  corners  all  wires 
shall  be  tied  to  the  side  groove  of  the  insulator  away  from  the  strain, 
so  that  the  insulator  and  not  the  tie  wire  shall  take  the  strain  of 
the  wires,  as  shown  in  Fig.  389.  No  tie  wires  shall  ever  be  replaced 
on  a  line  after  having  been  removed  therefrom,  as  second-hand 
tie  wires  are  hard  and  brittle  and  difficult  to  attach  properly  to 
the  line.  For  ordinary  strains  use: 

[  714  ] 


LINE  CONSTRUCTION 


Sec.  10 


No.  6  tie  for  No.  6  line  wire 

No.  6  tie  for  No.  4  line  wire 

No.  4  tie  for  No.  2  line  wire 

No.  4  tie  for  No.  1  line  wire 

No.  2  tie  for  No.  00  and  larger  line  wires. 

Methods  of  tying  are  shown  in  Figs.  390  and  391, 


1 


, 


104.  Splicing  Wires.     Every  joint  and  tap  shall  be  carefully 
soldered  and  tapped.     Mechanical  connections  shall  be   used  on 
medium  or  hard-drawn  copper  wires. 

105.  The  splicing  of  two  pieces  of  line  wire  shall  be  so  done  as  to 
be  mechanically  and  electrically  secure  without  the  use  of  solder. 

[  715  ] 


Sec.  W) 


LINE  CONSTRUCTION 


PI6-TAIL  Of  ffOLO/N6~DOIVN 

FOR  ALUMINUM  CONDUCTOR  USE 
STRANDS  or  2I400QCJ1.  ALUM- 
INUM CABLE  FOK  HOLDING-DOWN  Tie. 
Foe  COPPCR  CONDUCTOR  USE  *JO 

N.B.3.  ANNEALED  TELEPHONE 

Wl*E  OK  ANNEALED  STRANDS  OF  *00 

COWER  CABLE.  ABOUT  4$ rr  or 

WIRE  NECESSARY. 


Tie  Wiee 


FIG.  390.— Ties. 

Solid  wire  joints  shall  be  made  as  shown  in  Fig.  392.  The  two  ends 
to  be  spliced  shall  be  scraped  perfectly  clean  and  free  from  insulation 
for  the  length  necessary,  then  give  one  complete  long  wrap,  followed 
by  four  complete  close  wraps  about  each  other.  The  ends  of  the 
wrap  shall  then  be  cut  close  to  the  line  wire  and  the  entire  joint 
thoroughly  cleansed  and  well  soldered  with  pure  ^  and  ^  solder. 
Wipe  off  soldered  burrs  from  lower  ends  of  joint  and  cover  the 

[716] 


LINE  CONSTRUCTION 


Sec.  10 


entire  joint  with  standard  tape.  Give  the  same  amount  of  insulation 
as  that  on  the  line  wire.  Tape  wrappings  will  stick  better  to  the  joint 
if  made  while  the  latter  is  still  hot  from  the  application  of  solder. 

106.  Stranded  cable  splices  shall  be  as  shown  in  Fig.  393.  Scrape 
perfectly  clean  and  free  from  insulation  a  length  of  20  inches  to 
24  inches  at  the  end  of  the  cables  to  be  spliced.  Spread  the  wires 
and  pull  each  one  straight,  then  cut  out  the  core  of  each  cable. 


LINE  W/i?£ 


Tl£  WlK£ 


T/£W/K£ 


FIG.  391.— Ties. 


Take  the  strand  of  each  cable  in  groups  of  two  wires  each  and  alter- 
nately interweave  them,  laying  all  the  ends  closely  along  the  cable. 
Then  taking  each  group  of  two  strands  in  turn,  wrap  them  about 
the  interwoven  cables  until  all  the  ends  have  been  wrapped.  When 
completed,  the  joint  should  be  about  9  inches  long.  Solder  and  tape 
as  specified  above. 


[717] 


Sec.  10  LINE  CONSTRUCTION 


FIG.  392.— Solid  wire  splices  and  taps. 
[718] 


LINE  CONSTRUCTION 


Sec.  10 


FIQ.  393. — Stranded  cable  splice  and  tap. 
[  719  ] 


Sec.  10  LINE  CONSTRUCTION 

107.  Taps.     A  tap  from  a  line  shall  be  made  in  one  of  the  two 
following  methods:    When  the  wires  are  small  the  tap  shown  in 
Fig.  392  third  method,  is  the  better.     This  tap  is  made  by  giving 
the  branch  wire  one  complete  long  wrap,  followed  by  four  complete 
close  wraps,  about  the  line  wire.     Solder  and  tape  as  specified  above. 
For  large  solid  wires  and  cables,  the  wrapped  joint  shown  in  Fig. 
392,  fourth  method,  may  be  used.     The  line  wire  and  branch  wires 
are  scraped  clean  for  lengths  of  about  4  inches,  laid  closely  together 
and  bound  with  No.  12  &  B.   S.  bare  copper  wire.     Solder  and  tape 
as  specified  above.     A  cable  tap  may  be  made  as  shown  in  Fig. 
393. 

108.  Branch  Lines.     When  only  one  or  two  wires  branch  from  a 
pole,  the  tap  may  be  made  by  the  use  of  spreader  brackets,  as  shown 
in  Fig.  394.     If  the  branch  line  carries  more  than  two  wires,  a  buck 
arm  shall  be  used. 

109.  Spreader  Brackets.     Spreader  brackets  shall  be  fastened 
to  the  crossarms  with  four  ^-inch  carriage  bolts. 

110.  Pole  Wiring.     All  taps  and  connecting  wires  passing  from 
one  level  to  another  on  a  pole  shall,  so  far  as  possible,  be  made 
vertical.     All  taps,  branch  wires  and  loops  crossing  from  one  side 
of  a  pole  to  the  other  shall  cross  the  same  horizontally.     They  shall 
also  be  made  on  one  side  of  the  pole  only,  namely,  the  cross-arm  side, 
in  order  to  keep  the  back  of  the  pole  free  for  climbing. 

111.  Neat  Work.     All  bends  in  wires  shall,  if  possible,  be  at  right 
angles.  .  When  strung  in  position,  all  wires  shall  be  entirely  free 
from  crooks  and  kinks  and  shall  not  hang  loosely  between  supports. 
Loosely  hung  or  kinked  wires  are  not  only  unsightly,  but  are  in- 
dicative of  poor  line  work.     Carrying  wires  across  the  face  of  a 
pole  at  right  angles  and  necessarily  without  proper  supports,  not 
only  increases  the  liability  to  trouble  and  makes  trouble  hunting 
and  repair  work  difficult  in  the  confusion  of  wires,  but  necessarily 
makes  the  wires  an  eyesore  to  the  public. 

112.  Line  Terminals.     At  line  terminals  the  wires  shall  be  dead 
ended  on  the  back  pin  and  firmly  back  tied  on  the  front  pin.     To 
aid  front  pin  in  taking  its  share  of  the  strain,  the  tie  shall  be  put 
on  the  front  pin  as  firmly  as  possible  before  the  block  and  tackle 
used  in  pulling  up  the  line  wire  is  removed.     A  stranded  cable 
dead  end  shall  be  soldered  before  the  block  and  tackle  or  jack  strap 
are  removed. 

113.  Corners.     At    right-angle    corners    in    heavy    lines,    when 
possible,  turn  by  means  of  two  poles  as  shown  in  Fig.  376.     A  corner 
with  only  one  pole  may  be  turned  as  shown  in  Fig.  387.     The 
double  arm  may  be  omitted  if  necessary,  to  provide  space  for 
climbing.     When  guys  will  hold  the  pole  securely,  the  line  wires 
can  be  pulled  tightly  around  the  corner,  but  when  guys  are  weak, 
the  strain  of  the  wire  shall  be  correspondingly  lightened. 

[  720  ] 


LINE  CONSTRUCTION 


Sec.  10 


114.  Dead  Wires.  All  wires  temporarily  out  of  service  shall  be 
left  on  the  poles,  but  shall  be  cut  dead,  as  their  connection  to  a 
circuit  carrying  current  only  needlessly  increases  the  chance  of 
trouble  on  the  lines.  Wires  permanently  out  of  service  shall  be  at 
once  entirely  removed  from  the  poles. 


FIG.  394. — Branch  tap  line  with  spreader  brackets. 


115.  Reinforcing  Wires.  When  line  or  service  wires  become  too 
small  for  their  work  and  additional  copper  must  be  strung,  the  line 
shall  not  be  reinforced  by  stringing  additional  wires  on  the  same 
pins.  Preferably,  the  old  wires  shall  be  removed  from  the  line  and 

[721] 


Sec.  10  LINE  CONSTRUCTION 

new  wires  of  proper  size  strung  in  their  places,  thus  keeping  the 
actual  number  of  wires  on  the  fine  at  a  minimum. 

116.  SYSTEMS  OF  DISTMBUTION.     Commercial  circuits  shall 
be  designed  to  furnish  practically  uniform  voltage  throughout  a 
system  of  distribution.     Otherwise,  satisfactory  lighting  or  power 
service  cannot  be  supplied  to  consumers.     To  secure  this  end  so  far 
as  possible,  all  constant  potential  circuits  shall  be  laid  put  on  the 
feeder  and  main  system,  feeders  being  run  from  the  station  or  sub- 
station to  some  point  of  distribution  centrally  located  in  the  district 
to  be  supplied.     From  this  center  of  distribution  the  mains  should 
radiate  in  such  a  manner  and  be  of  such  a  size  that  the  drop  in 
potential  therein  will  be  as  uniform  as  possible,  and  as  low  as  is 
warranted  by  the  costs  of  construction.     The  drop  of  potential  in 
the  feeder  between  station  or  substation  and  the  center  of  distribu- 
tion, at  time  of  maximum  load,  shall  not  exceed  ten  percent  of  the 
delivered  voltage,  this  Targe  drop  being  permissible  only  when  separate 
feeder  regulators  are  installed. 

117.  In  general,  consumers  shall  not  be  connected  to  feeders  when 
they  can  be  supplied  from  distributing  mains  or  branches. 

118.  Branch  lines  or  mains  on  the  500-volt  power  circuits  shall 
be  tied  together  as  far  as  possible,  thereby  providing  an  inter- 
connected network  of  wires  throughout  a  district.     Branch  lines  or 
mains,  however,  supplied  by  separate  feeders,  shall  not  be  so  inter- 
connected. 

119.  CARRYING  CAPACITY.     The  wires  shall  be  of  a  size  that 
the  carrying  capacity,  as  specified  in  Table,  24,  Sec.  3,  shall  be  amply 
sufficient  for  the  load  on  each  feeder,  main  or  branch,  reasonable 
allowance  being  made  on  new  lines  for  increase  in  load  due  to  future 
extensions  of  the  business. 

120.  LINES  ON  PRIVATE  PROPERTY.     When  lines  or  service 
connections  are  run  upon  private  property,  either  by  the  company 
or  by  others,  to  connect  to  the  lines  of  the  company,  whether  paid 
for  in  whole  or  in  part  by  the  company  or  by  the  owner  of  the 
property,  the  construction  work  thereon  shall  be  done  in  each  case, 
and  in  every  particular,  in  accordance  with  the  standard  line  spe- 
cifications. 

LOCATION  OF  WIRES 

121.  Series  Circuits.     Every  series  circuit  shall  start  from  station, 
substation,  or  other  point  of  distribution,  on  a  given  pin  and  cross- 
arm,  and  shall  follow  this  same  relative  pin  and  cross-arm  throughout 
its  course.     Circuits  shall  not  jump  from  one  location  on  a  cross- 
arm  to  another  location  on  the  same  cross-arm,  nor  to  a  different 
cross-arm,  but  shall  always  be  placed  on  their  proper  pin.    Such  a 
system  of  confining  each  circuit  to  a  given  pin  throughout  its  course 
makes  trouble  hunting  and  repair  work  much  simpler  than  they 

[722] 


LINE  CONSTRUCTION  Sec.  10 

otherwise  would  be  and  is  the  only  possible  way  which  circuits 
can  be  constructed)  maintained,  operated  and  extended  in  a  satis- 
factorily systematic  manner.  As  series  arc  and  series  incandescent 
circuits  are  cut  dead  during  the  daytime  and  will  not.  therefore, 
hamper  linemen  working  on  a  pole,  these  circuits  can  often  be  run 
to  advantage  on  the  pole  pins  of  the  cross-arm.  Such  an  arrange- 
ment is  also  convenient  for  making  lamp  loop  connections.  It 
should  be  noted  that  as  it  is  the  usual  practice  to  ground  all  constant 
current  series  circuits  in  the  station,  that  these  wires  should  be 
considered  as  grounded  wires  by  linemen  when  working  on  the 
poles,  this  in  addition  to  the  general  rule  that  all  wires  shall  be 
treated  as  being  alive  at  all  times. 

122.  Multiple  Circuits.     The  wires  of  commercial  circuits  shall 
retain  the  same  relative  position  on  pins  and  cross-arms  throughout 
their  course  and  shall  not  jump  from  one  set  of  pins  to  another 
set  on  the  same  cross-arm,  nor  from  one  cross-arm  to  another  cross- 
arm. 

123.  Locations  on  Pins.    The  two  wires  of  each  circuit  shall  be 
run  on  adjacent  pins  of  the  crossarm,  as  these  circuits  are  operated 
continuously  day  and  night.     2300-volt  circuits  shall  preferably  be 
located  on  the  adjacent  pins  at  the  ends  of  a  cross-arm  to  keep  line 
work  as  straightforward  as  possible;    and  to  simplify  street  lamp, 
transformer  and  service  connections,  all  through  feeders  shall  be 
placed  on  the  upper  cross-arms  of  a  trunk  line  as  far  as  possible,  and 
all  circuits  feeding  the  territory  through  which  the  line  passes  shall 
be  located  on  the  lower  cross-arms.     500-volt  wires  can  often  be 
advantageously  located  on  the  pole  pins  at  the  center  of  a  cross-arm. 

124.  Temporary  Work  to  be  Avoided.     All   construction   and 
extension  work  on  circuits  shall  be  of  a  permanent  character,  both 
as  to  the  routes  followed  and  the  quality  of  line  work.     Rush  work, 
short  cuts,  skimped  materials  and  other  such  attempts  to  hasten 
the  completion  or  reduce  the  initial  cost  of  circuit  extension  shall  be 
avoided.     Temporary  makeshifts  in  line  construction  necessitate 
frequent  repairs  and  changes,  are  a  continual  source  of  trouble, 
interrupt  service,  annoy  both  company  officials  and  consumers  and, 
in  the  end,  always  cost  more  than  permanently  laid  out,  well-built 
lines. 


[723] 


SECTION  10 


PART  II 

SPECIFICATIONS  COVERING  METHODS   OF   OVER- 

HEAD  LINE  CONSTRUCTION  FOR  SECONDARY 

VOLTAGES,    INCLUDING     POLE    WIRING 

FOR    STREET-LIGHTING    WORK. 


SECTION  10 

PART  II 

SPECIFICATIONS    COVERING    METHODS    OF    OVERHEAD 
LINE  CONSTRUCTION  FOR  SECONDARY  VOLT- 
AGES, INCLUDING  POLE  WIRING  FOR 
STREET-LIGHTING  WORK. 


TABLE  OF  CONTENTS 

AKTICLE 
Stringing  of  Secondary  Wires , 1  to  7 

Installations  of  Transformers,  Fuse  Blocks,  etc 

When  to  use  transformers  individually 8  to  10 

When  to  use  more  than  one  transformer 11  to  14 

Method  of  Erection  of  Transformers 15  to  21 

Fuse  Blocks 22  to  29 

Lightning  Arresters 30  to  33 

Consumers'  Services 34  to  39 

Pole  Wiring  for  Street  Arc  Lamps 40-41 

Pole  Wiring  for  Street  Incandescent  Lamps 42-43 


SPECIFICATIONS   COVERING   METHODS  OF  OVER- 
HEAD LINE  CONSTRUCTION  FOR  SECONDARY 
VOLTAGES,     INCLUDING     POLE     WIRING 
FOR    STREET-LIGHTING     WORK 

METHODS  OF  SECONDARY  SYSTEM  WORK 
STRINGING  OF  SECONDARY  WIRES 

1.  Secondary  wires  in  all  systems  shall  be  located  below  the 
lowest  arm  carrying  primary  wires  or  series  lighting  wires. 

2.  Secondary  wires  of  the  same  circuit,  if  carried  on  cross-arms 
shall  be  attached  to  adjacent  pins.     If  secondary  racks  are  used, 
Figs.  409  to  411,  they  shall  be  located  below  the  lowest  arm  on 
the  pole.     The  secondary  wires  shall  be  so  located  that  the  crossing 
of  the  pole  will  be  avoided  as  much  as  possible;  viz.,  on  the  side  of 
the  pole  from  which  the  greater  number  of  consumers  will  be  cut  in. 

3.  When    running     single-phase,     two-wire     secondary     mains, 
attached  to  cross-arms,  the  wires  shall  be  placed  on  the  two  end 
pins  on  the  side  nearer  the  greater  number  of  consumers. 

4.  When  running  single  phase  three  wire  secondary  mains  attached 
to  cross-arms,  the  wires  shall  be  placed  on  the  three  end  pins  with 
the  neutral  wire  in  the  center. 

When  running  single  phase  three  wire  secondary  mains,  on  se- 
condary racks,  the  neutral  wire  shall  be  in  the  top  position. 

5.  When  running  two-phase,  three- wire  or  four- wire,  or  three- 
phase,  three-wire,  secondary  mains,  the  wires  shall  be  placed  in  the 
same  relative  position  as  described  for  three-wire,  single-phase  work. 

6.  When  running  secondary  mains  where  there  is  a  probability 
of  change  to  a  system  requiring  additional  wires,  it  is  desirable  to 
so  locate  the  wires  that  vacant  pins  will  be  left,  which  will  permit 
the  running  of  the  additional  wires  without  disturbing  existing  wires. 

7.  220-volt  secondary  mains  shall  not  extend  more  than  600 
feet  in  any  direction  from  a  transformer,  although  the  secondary 
mains  may  be  extended  to  a  greater  distance  by  banking  trans- 
formers, when  load  conditions  make  it  desirable. 

INSTALLATION  OF  TRANSFORMERS,  FUSE 
BLOCKS,  ETC. 

When  to  Use  Transformers  Individually 

8.  When  consumers  are  too  great  a  distance  apart  for  the  econom- 
ical running  of  secondary  mains,  individual  transformers  shall  be 
used. 

9.  Individual  transformers  shall  also  be  used  for  large  power 
loads  and  where  the  load  is  intermittent  or  of  such  a  character  as  to 
interfere  with  the  proper  regulation  of  voltage  on  the  secondary 
mains. 

[  729  ] 


Sec.  10 


LINE  CONSTRUCTION 


10.  Loads  which  are  likely  to  disturb  voltage  regulation  will 
occur  in  installations  of  elevator  motors,  electrically  operated  cranes, 
welding  machines,  electrical  furnaces,  moving  picture  lamps,  etc. 

When  to  Use  More  Than  One  Transformer 

11.  It  is  desirable  to  use  more  than  one  transformer,  connecting 
them  in  parallel,  when  the  center  of  distribution  on  the  section  of 
the  secondary  main  is  changeable,  due  to  the  varying  load  conditions 


FIG.  395. — Individual  transformer  installation. 

of  the  individual  consumers  connected,  although  under  such  con- 
ditions the  average  maximum  demand  on  the  transformers  will  be 
comparatively  constant. 

12.  In  selecting  transformers  for  parallel  operation,  it  is  desirable 
to  have  them  of  the  same  regulating  characteristics,  which  can  best 
be  obtained  by  having  them  of  the  same  make,  type,  form,  etc., 
and,  if  possible,  of  the  same  size  and  series. 

[730] 


LINE  CONSTRUCTION 


Sec.  10 


13.  The  limiting  of  the  number  of  transformers  to  be  used  in  a 
bank  for  multiple  operation  shall  be  determined  by  the  relation  of 
the  load-factor  of  the  individual  consumer  to  the  total  load-factor 
of  the  bank  of  transformers,  having  in  mind  the  difference  in  the 


FIG.  396. — Individual  transformer  installation. 

time  of  day  of  the  maximum  demand  of  the  individual  consumers 
connected  to  the  bank. 

14.  The  danger  of  putting  too  many  consumers  on  one  bank  of 
transformers  is  that  the  service  of  all  may  be  interrupted  in  case 
of  accident  to  one  or  more  transformers. 

[731] 


Sec.  10 


LINE  CONSTRUCTION 


[732] 


LINE  CONSTRUCTION 


Sec.  10 


Transformers  which  are  operated  in  parallel  may  be  fed  from  a 
primary  loop,  so  arranged  that  all  the  transformers  connected  in 
parallel  can  be  disconnected  by  a  single  disconnecting  switch  or 
fuse  block. 


Method  of  Erection  of  Transformers 

15.  It  is  undesirable  to  erect  more  than  one  transformer  on  a 
pole,  and  the  transformer  shall  be  supported  by  suitable  irons  which 
pass  over  the  cross-arm  supporting  the  transformer.  This  arm  may 

[733] 


Sec.  10 


LINE  CONSTRUCTION 


be  the  top  arm  on  the  pole  or  the  lowest  primary  arm  on  the  polo 
when  the  transformer  is  fed  from  a  circuit  carried  on  the  arm  from 
which  it  is  hung,  or  when  high  poles  are  used  special  transformer 
arms  may  be  placed  below  the  secondary  arms,  usually  at  a  point 
midway  between  the  top  arm  and  the  ground,  but  in  any  event, 
not  lower  than  twenty  feet  from  the  ground. 

16.  Transformers  shall  be  supported  from  the  central  point  of 
the  arm  and  not  hung  out  on  the  arm  away  from  the  pole. 

17.  It  is  undesirable  to  hang  from  an  arm  transformers  exceeding 
25  kilowatts  in  capacity,  and  where  such  special  cases  occur,  re- 


FIG.  401.— ^Special  iron  braces  for  three  transformers. 


quiring  transformers  in  excess  of  this  capacity,  special  supporting 
construction  shall  be  installed. 

18.  Where  special  conditions  make  it  necessary  to  hang  more 
than  one  transformer  on  a  pole,  if  the  requirements  do  not  exceed 
transformers  of  greater  capacity  than  10  kilowatts,  they  shall  be 
hung  on  each  side  of,  but  near,  the  pole,  and  never  placed  back  to 
back. 

19.  When    special    conditions    require    the    installation    of   two 
transformers  on  a  pole,  each  of  a  capacity  greater  than  10  kilowatts, 
they  shall  not  be  supported  from  the  cross-arms  on  either  side  of  the 
pole,  as  in  the  case  of  10  kilowatts  and  under,  but  each  large  trans- 

[  734  ] 


LINE  CONSTRUCTION 


Sec.  10 


former  shall  be  hung  from  separate  cross-arms  at  the  pole,  thus 
placing  the  transformers,  one  above  the  other. 

20.  All  wiring  work  in  connection  with  the  installation  of  trans- 
formers shall  be  done  with  not  less  than  No.  6  double  braid,  rubber- 
covered  wire. 

21.  All  poles  carrying  transformers  shall  be  double  armed  for 
the  transformer  work. 


I 


[  735  ]    i   , 


Sec.  10 


LINE  CONSTRUCTION 

Fuse  Blocks 


22.  To  protect  both  the  primary  wire  and  the  transformer,  a 
single-pole  fuse  block,  preferably  of  the  porcelain  variety,  shall  be 
inserted  in  each  leg  of  the  primary  circuit  when  connection  is  made 
to  transformer. 

23.  Fuse  blocks  may  be  placed  at  the  head  of  all  branch  circuits, 
thus  confining  trouble  on  a  branch  circuit  to  the  branch  developing  it. 

24.  Fuse  blocks  shall  be  located  on  the  arm  or  on  rear  double 
arm  from  which  the  transformer  is  supported,  and  shall  always  be 
bolted  to  the  crossarm  by  means  of  galvanized  iron  bolts  not  less 
than  }/^-inch  in  diameter  and  usually  approximately  4H  inches  long. 

25.  Fuse  blocks  protecting  transformers  of  three  kilowatts  capacity 
and  over,  shall  be  of  a  capacity  equal  to  one  ampere  per  kilowatt  of 


IL  HI 


FIG.  403. — Special  transformer  rack. 

the  transformer  protected,  when  primary  voltage  is  approximately 
2300  volts. 

26.  No  fuse  block  shall  have  a  smaller  carrying  capacity  than  one 
ampere. 

27.  Transformers  from  0.6  kilowatt  to  1.5  kilowatt  capacity  may 
be  protected  by  a  two-ampere  fuse  block,  and  transformers  from 
two  kilowatts  to  three  kilowatts  may  be  protected  with  a  three- 
ampere  fuse  block;   although  it  is  also  good  practice  to  protect  all 
transformers  up  to  three  kilowatts  capacity  with  three-ampere  fuse 
blocks. 

28.  The  capacity  of  fuse  blocks  at  the  head  of  branch  circuits 
will  be  determined  by  the  load  upon  the  branch  circuit  to  be  pro- 

[736] 


LINE  CONSTRUCTION 


Sec.  10 


[737] 


LINE  CONSTRCUTION 


*it mm 


FIG.  407. — Installation  of  three  transformers. 
[  738  ] 


LINE  CONSTRUCTION 


Sec.  10 


FIG.  408. — Vortical  secondary  distribution. 


\ 


FIG.  4()9. — Vertical  secondary  distribution. 


I  739  ] 


Sec.  10 


LINE  CONSTRUCTION 


[740] 


LINE  CONSTRUCTION 


Sec.  10 


1 1, 


[741] 


Sec.  10 


LINE  CONSTRUCTION 


[742] 


LINE  CONSTRUCTION 


Sec.  10 


[743-] 


Sec.  10 


LINE  CONSTRUCTION 


[744] 


LINE  CONSTRUCTION  Sec.  10 

tected,  but  in  no  case  shall  fuse  blocks  so  placed  exceed  seventy-five 
percent  of  the  capacity  of  the  station  fuse. 

29.  All  wiring  work  in  connection  with  fuse-block  installations 
shall  be  done  with  not  less  than  No.  6  double  braid,  rubber-insulated 
wire. 

LIGHTNING  ARRESTERS 

30.  Lightning  arresters  shall  not  be  installed  on  poles  carrying 
transformers,  nor  on  poles  at  the  head  of  branch  lines,  but  shall 
preferably  be  placed  on  the  pole  next  adjacent  to  the  transformer 
or  head  branch-line  pole. 

31.  Lightning  arresters  shall  be  bolted,  not  screwed,  to  the  sides 
of  the  crossarms. 

32.  Ground  connections  for  the  arresters  shall  be  carried  down 
the  pole,  in  a  solid  insulating  conduit,  in  order  to  afford  all  possible 
protection  to  linemen  working  on  the  poles,  as  well  as  protection 
to  the  passer-by  who  might  come  in  contact  with  the  ground-wire 
covering. 

33.  Lightning  arrester  ground  wires  should  never  be  run  in  metal 
pipes.     For  methods  of  grounding,  see  Sec.  6,  Part  II. 

All  wiring  on  poles  in  connection  with  the  installation  of  lightning 
arresters  shall  be  done  with  not  less  than  No.  6  double  braid  rubber 
insulated  wire. 

CONSUMERS'  SERVICES 

34.  Service  loops  from  a  pole  to  a  building  may  be  made  with 
suitable  cable  of  more  than  one  conductor,  or  with  individual  leads. 

35.  The  use  of  cable  makes  a  better  looking  job,  as  well  as  minim- 
izes the  number,  and  in  many  cases  the  size,  of  building  attachments, 
but  its  use  should  be  limited  to  loops  not  exceeding  1 00  feet  in  length, 
and  should  not  be  used  in  sizes  of  wj^e  larger  than  No.  4,  unless  the 
service  loops  are  very  ^hort. 

36.  The  use  of  single-wire  leads  is  desirable  for  long  loops,  for 
loops  requiring  large  copper,  and  in  installations  where  the  additional 
cost  of  a  cable  is  unwarranted,  or  where  special  physical  conditions, 
such  as  interfering  trees  or  structures,  make  cable  work  undesirable. 

37.  Overhead  service  wires  or  cables  may  be  cut  in  from  secondary 
systems  by  either  one  of  three  methods: 

1st.     By  the  use  of  buck  arms. 

2nd.    By  the  use  of  spreader  brackets. 

3rd.     By  the  use  of  secondary  racks. 

When  the  secondary  system  is  run  on  crossarms,  it  is  necessary 
to  use  either  the  first  or  second  method.  The  second  method,  or  the 
use  of  spreader  brackets,  is  advised  because  of  its  more  sightly 
appearance,  and  if  used,  the  wires  should  be  carried  across  the  pole 
to  the  end  of  the  arm,  in  such  a  manner  that  at  all  times  they  will 
clear  all  other  wires  by  at  least  43/£  inches,  and  should  be  continued 
from  the  arm  to  the  first  point  of  attachment  to  the  building  or 
consumers  service  connection,  in  as  direct  a  line  as  possible,  making 
the  run  as  nearly  as  practicable  in  a  horizontal  direction, 

[745] 


Sec.  10 


LINE  CONSTRUCTION 


When  the  secondary  system  is  carried  on  secondary  racks,  the 
overhead  service  wires  or  cables  shall  be  cut  in  from  the  secondary 
rack  in  such  a  manner  as  to  secure  the  proper  fastening  of  the  wires. 
Should  it  be  necessary  to  cross  the  pole,  a  second  secondary  rack 
may  be  installed  on  the  opposite  side  of  the  pole  connecting*  both 
racks  together,  thus  permitting  the  running  of  service  connections 
in  all  directions  in  a  workmanlike  manner. 

In  order  to  balance  the  side  strain  on  the  poles  from  which  service 
wires  are  run,  guy  wires  should  be  installed,  or  effort  should  be  made 


Fia.  420. — Single  wire  incandescent  lamp  leads. 

to  so  install  service  connections  that  the  strain  resulting  therefrom 
is  equalized. 

38.  All  connections  between   the   transformer  and   the  outlets 
shall  be  properly  spliced,  soldered  and  taped,  as  described  in  Arts. 
104  to  107,  Sec.  10,  Part  I. 

39.  Underground  service  connections  from  overhead  lines  shall 
be  run  down  the  pole  in  a  pipe,  which  from  a  point  10  feet  above 

[746] 


LINE  CONSTRUCTION 


Sec.  10 


FIG.  421. — Line  entrance  bushings.     (Sub-station.) 


FIG.  422.— Turning  a  90°  bend  on  two  poles. 


[747] 


Sec.  10 


LINE  CONSTRUCTION 


the  ground  to  the  cross-arm,  shall  be  of  a  suitable  insulating  conduit, 
in  order  to  afford  all  possible  protection  to  linemen  working  on  the 
pole. 

POLE  WIRING  FOR  STREET  ARC  LAMPS 

40.  The  wiring  from  the  cross-arm  to  an  arc  lamp  shall  be  done 
with  rubber-covered  duplex  cable  and  the  same  shall  be  rigidly 


FIG.  423.— Turning  a  90°  bend  on  one  pole. 


supported  on  insulators  attached  to  metal  brackets  so  that  the 
perpendicular  run  of  the  wire  may  be  rigid  and  the  wire  will  be  held 
five  inches  from  the  pole  throughout  its  run. 

41.  The  portion  of  the  cable  looped  from  the  pole  to  the  lamp 
shall  not  exceed  a  length  necessary  to  lower  the  lamp  for  trimming 
purposes  without  straining  the  cable. 

[748] 


LINE  CONSTRUCTION  Sec.  10 

POLE  WIRING  FOR  STREET  INCANDESCENT  LAMPS 

42.  The  wiring  from  a  cross-arm  to  an  incandescent  lamp  shall 
be  done  with  rubber-covered  duplex  cable  and  the  same  shall  be 
rigidly  supported  on  insulators  attached  to  metal  brackets  so  that 
the  perpendicular  run  of  the  wire  may  be  rigid  and  the  wire  will  be 
held  five  inches  from  the  pole  throughout  its  run. 

43.  The  perpendicular  run  of  the  cable  lead  shall  extend  down 
the  pole  to  a  point  opposite  the  point  of  support  on  the  incandescent 
lamp  fixture  and  the  run  from  the  pole  to  the  fixture  shall  be  parallel 
to  the  ground  line  and  sufficiently  tight  to  insure  neat  appearance  of 
workmanship. 


[749] 


SECTION  11 


PART  I 
METEOROLOGICAL  AND  GENERAL  DATA 


PART  II 

RULES  FOR  RESUSCITATION  FROM 
ELECTRIC  SHOCK 


SECTION  11 
PART  I— METEOROLOGICAL  AND  GENERAL  DATA 


TABLE  OF  CONTENTS 

Storm  Movements  ARTICLE 

General 1 

Weather  Map  Symbols 2 

The  Weather  Map 3 

Interpretation  of  the  Weather  Map 4 

The  Thunderstorm 5 

Phenomena  of  Lightning 6 

Causes  of  the  Strong  Uprushing  Air  Currents 7 

Time  and  Localities  Favoring  Thunderstorms 8 

Rain 9 

Snow 10 

Hail 11 

Ice  Storms 12 

Sleet 13 

Table  112. — Monthly  Mean  Maximum  Temperature.* 
Table  113. — Monthly  Mean  Minimum  Temperature.* 
Table  1 14. — Total  Number  of  Days  with  Maximum  Temper- 
ature 90°  or  above.* 

Table  115. — Total  Number  of  Days  with  Minimum  Temper- 
ature zero  or  below.* 
Table  116.— Highest    Wind    Velocities    on    Record    with 

Direction.* 
Table  117.— Total  Number  of  Days  with  Maximum  Wind 

Velocity  of  40  miles  per  hour  or  more.* 
Table  118.— Total  Number  of  Thunderstorms.* 
Table  119.— Total  Number  of  Days  with  Dense  Fog.* 
Table  120.— Sleet  Data.* 

*  Tables  compiled  from  data  furnished  by  the  U.  S.   Dept.  of  Agriculture, 
Weather  Bureau.     Corrected  to  February  1st,  1914. 

[753] 


Sec.  11  METEOROLOGICAL  DATA 

ARTICLE 

Discussion  of  Sleet  Data .- 14 

Table  121.— Wind  Velocity  Correction  Table.* 

Corrections  of  Barometric  Pressure 15 

Table  122. — Barometric  Corrections.* 

Hot  Galvanizing 16 

Sherardizing 17 

Specification  for  Galvanizing  Iron  or  Steel 18 

Concrete..                                                                                     .  19 


*  Tables  obtained  from  the  U.  S.  Dept.  of  Agriculture,  Weather  Bureau. 

[754] 


The  importance  of  meteorological  data  is  not  generally  appreciated 
by  lighting  and  power  companies,  particularly  in  sections  and  during 
seasons  when  transportation  may  be  affected,  or  in  localities  subject 
to  tornadoes,  thunderstorms,  sleet  storms,  etc.  A  compilation  of 
data  covering  such  phenomena  has  been  secured  through  the  co- 
operation of  the  United  States  Weather  Bureau,  Department  of 
Agriculture,  but  inasmuch  as  these  data  are  collected  from  observing 
stations,  generally  located  in  built-up  sections  of  important  cities, 
the  official  records  do  not  necessarily  indicate  the  maximum  wind 
velocities,  etc.,  which  may  be  obtained  in  open  country.  They  are  of 
importance,  however,  in  that  they  indicate  the  probable  frequency  of 
high  winds,  sleet  storms,  maximum  and  minimum  temperatures,  etc. 

In  addition  to  the  above  tabulation,  a  general  description  of  storm 
movements  and  atmospheric  phenomena,  has  been  prepared  by 
representatives  of  the  Weather  Bureau,  which  information  is  of 
particular  importance  in  interpreting  weather  maps  and  other  data 
issued  by  that  Bureau . 

STORM  MOVEMENTS* 

1.  General.     The  Weather  Bureau  maintains  something  over  200 
telegraphic  observing  stations  which  are  distributed  over  the  entire 
country.     Observations  are  taken  at  these  points  every  12  hours 
and  the  results  are  transmitted  by  telegraph,  in  code  form,  to  the 
Central  Office  in  Washington,  and  are  interchanged  between  all 
of  the  larger  stations  at  which  daily  weather  maps  are  published. 
So  thoroughly  has  the  telegraphic  system  been  worked  out  that  the 
entire  distribution  is  ordinarily  made  in  one-and-one-half  hours, 
and  in  two  hours  after  each  observation  the  forecasters  have  mapped 
the  atmospheric  survey  and  are  prepared  to  forecast   probable 
movements  and  developments  for  36  to  48  hours  in  advance.     Such 
a  system  enables  the  forecaster  to  follow  the  storm  movements 
closely,  and  to  forecast  for  another  state  or  a  distant  city  with  nearly 
as  high  a  degree  of  accuracy  as  can  be  done  for  his  own  locality. 

2.  Weather  Map  Symbols.     The  locations  of  the  observing  sta- 
tions are  indicated  by  small  circles.     Where  cloudiness  prevails  the 
whole  area  of  the  circle  is  blackened ;  for  partly  cloudy  conditions, 
one-half  of  the  circle  is  blackened;   while  the  whole  is  left  clear  to 
represent  clear  skies.     If  rain  is  falling  at  the  time  of  observation 
an  "R"  is  marked  in  the  circle,  or  an  "S"  for  snow,  as  the  case  may 
be.     Arrows  are  inscribed  to  note  the  direction  of  the  wind. 

The  barometer  reading,  temperature,  wind  velocity  in  miles  per 
hour,  and  the  depth  of  precipitation  (rain  or  snow),  if  any,  are 
written  by  the  side  of  each  station  in  figures.  The  precipitation 
areas  are  outlined  and  shaded.  Red  lines  are  drawn  through  points 

*U.  S.  Dept.  of  Agriculture,  Weather  Bureau,  Forcasting  the  Weather  by 
Geo.  S.  Bliss. 

[755] 


Sec.  11  METEOROLOGICAL  DATA 

of  equal  barometric  readings,  and  indicate  atmospheric  disturbances. 
Blue  lines  are  drawn  through  points  of  equal  temperature  and  the 
completed  chart  is  known  as  a  weather  map. 

3.  The  Weather  Map.  The  map  illustrated  (Fig.  424)  has  been 
selected  because  of  its  near  approach  to  a  theoretically  ideal  type 
illustrating  the  general  laws  applicable  to  atmospheric  disturbances. 

The  isobars,  or  lines  of  equal  barometer  readings,  form  the  most 
prominent  feature  of  the  map,  as  they  locate  the  great  centers  of 
action.  They  are  drawn  for  each  tenth  of  an  inch  of  variation. 
For  example,  the  line,  marked  "30.0"  at  each  end,  passes  through 
points  where  the  barometer  readings  are  just  30  inches.  On  one 
side  of  this  line  the  readings  are  higher  than  30  inches,  and  lines  are 
drawn  for  each  tenth  of  an  inch  increase  until  a  center  or  crest  is 
located  and  marked  "High."  On  the  other  side,  lines  are  drawn 
for  each  tenth  of  an  inch  decrease  until  the  center  of  the  depression 
is  located  and  marked  "Low."  The  isobars  outline  great  atmos- 
pheric whirls  or  eddies. 

It  will  be  noted  that  the  winds  blow  in  toward  the  center  of  the 
area  marked  "Low,"  not  directly,  but  spirally.  Also  that  the  winds 
rotate  about  the  center  in  a  direction  opposite  that  of  the  hands  of 
a  watch  face  upward.  Some  places  will  be  noted  where  the  winds 
do  not  conform  to  the  above  rules,  being  temporarily  deflected  by 
local  conditions.  The  more  intense  and  energetic  the  disturbance 
becomes  the  more  nearly  will  the  wind  movements  conform  to  the 
general  laws. 

In  the  area  marked  "High"  at  the  center  it  will  be  observed  that 
the  winds  move  in  an  opposite  direction  to  those  in  the  "Low." 
In  other  words,  they  blow  spirally  outward  from  the  center.  Also 
it  will  be  observed  that  the  air  currents  flow  in  a  compound  curve 
from  the  center  of  the  "High"  toward  the  center  of  the  "Low." 

Since  the  surface  winds,  as  indicated  by  the  arrows,  blow  in  toward 
the  center  of  the  "Low"  from  all  directions,  it  is  evident  that  the 
air  rises  in  the  central  area.  Conversely,  it  is  equally  evident  that 
the  air  is  constantly  settling  down  in  the  central  area  of  the  "High." 
The  fact  that  the  surface  air  currents  flow  from  the  center  of  the 
"High"  toward  the  center  of  the  "Low"  suggests  the  idea  that  at 
some  distance  above  the  earth  the  rising  air  in  the  "Low"  must 
flow  toward  the  "High"  and  such  is  the  case. 

The  interchange  of  air  as  noted  above  does  not  comprise  the 
complete  circulation  of  these  areas,  for  if  a  map  of  a  larger  territory 
were  prepared,  it  would  indicate  adjacent  disturbances  with  which 
the  same  relations  are  maintained. 

The  temperature  conditions  attending  such  an  atmospheric  cir- 
culation are  illustrated  by  the  freezing  line  (drawn  through  points 
having  a  temperature  of  32°  F.)  This  line  begins  in  the  extreme 
northeast  in  central  New  Brunswick,  and  extends  nearly  due 
westward  to  a  point  north  of  the  center  of  the  "low,"  and  thence 
sweeps  southward  nearly  t,o  the  Texas  coast,  then  northwestward 
into  southern  California,  whence  it  bears  northward  nearly  parallel 

[756] 


METEOROLOGICAL  DATA 


Sec.  11 


[75TJ 


Sec.  11  METEOROLOGICAL  DATA 

to  the  Pacific  coast  line.  A  study  of  the  wind  directions  with  re- 
lation to  this  line  will  suggest  some  of  the  reasons  for  its  trend. 

The  weather  conditions  in  these  large  atmospheric  whirls  are 
as  remarkable  as  are  the  temperature  conditions.  Prevailing 
cloudiness  is  general  in  the  low-pressure  area.  By  way  of  contrast 
clear  skies  are  general  over  the  greater  portion  of  the  high-pressure 
area.  Areas  of  high  and  low  barometric  pressure  are  constantly 
and  successively  drifting  across  the  country  from  the  west  toward 
the  east,  thus  causing  the  weather  changes. 

It  becomes  evident  that  while  an  area  of  low  barometric  pressure 
is  drifting  over  a  given  locality  the  weather  will  ordinarily  be  cloudy 
with  a  tendency  to  rain  or  snow,  depending  on  the  season  of  the 
year.  The  temperature  will  at  first  be  comparatively  high,  followed 
by  colder  when  the  center  of  the  area  has  passed  and  the  wind  shifts 
to  a  westerly  or  northwesterly  direction.  As  the  area  of  low 
pressure  passes  eastward  and  is  succeeded  by  an  area  of  high 
pressure,  the  temperature  will  continue  to  fall  for  a  time  and  the 
skies  will  clear. 

A  rapid  succession  of  high  and  low  pressure  areas  implies  frequent 
changes  in  weather  and  temperature  conditions,  while  conversely 
a  sluggishness  in  the  movements  of  these  areas  tends  toward  a 
prolongation  of  given  types  of  weather. 

4.  Interpretation  of  the  Weather  Map.  Many  changes  occur  in 
the  atmospheric  disturbances  during  their  progress  across  the  country, 
owing  to  the  continual  shifting  of  their  relative  location  with  regard 
to  mountains,  lakes,  the  seashore,  or  to  extensive  dry  plains.  Baro- 
metric pressure  areas  are  only  formations  through  which  the  at- 
mosphere circulates  and  they  do  not  carry  a  given  quantity  of  air 
with  them  across  the  continent . 

Weather  forecasting  consists  in  watching  the  storm  movements 
and  developments  by  means  of  the  weather  maps,  in  anticipating 
the  changes  that  will  take  place  in  them,  in  estimating  the  expanse 
of  territory  that  will  be  covered  and  the  time  that  given  points  will 
be  reached  thereby  determining  the  weather  conditions  that  may 
reasonably  be  expected  in  each  locality  during  the  ensuing  36  to  48 
hours.  A  chart  showing  average  storm  tracks  and  average  daily 
movements  in  the  United  States  is  illustrated  in  Fig.  425. 

About  60  per  cent  of  the  areas  of  low  barometer  in  the  United 
States  are  first  recorded  over  the  extreme  northwestern  portion  of 
the  country,  and  thence  they  move  eastward  along  the  northern 
route. 

When  a  low-pressure  area  is  central  over  Idaho,  for  example,  the 
precipitation  within  it  will  ordinarily  be  light,  inasmuch  as  the  air 
that  circulates  through  it  flows  in  from  comparatively  dry  regions. 
The  air  currents  from  the  Pacific  rise  rapidly  as  they  flow  inland 
and,  cooling  by  expansion,  they  are  deprived  of  a  large  portion  of 
their  moisture  on  the  western  side  of  the  Cascade  range  of  Mountains. 

When  the  center  of  the  disturbance  has  moved  eastward  across 
the  Rocky  Mountains  the  rainfall  begins  to  increase  in  the  eastern 

[  758] 


METEOROLOGICAL  DATA 


Sec.  11 


759  ] 


Sec.  11  METEOROLOGICAL  DATA 

side  of  the  area,  occasioned  by  the  greater  quantity  of  moisture  in 
the  atmosphere  that  flows  in  from  the  central  valleys  and  from  the 
western  portion  of  the  Lake  region.  From  thence  eastward  the 
storm  usually  increases  in  energy  as  it  reaches  into  lower  altitudes 
and  moister  regions,  but  ordinarily  these  disturbances  do  not  cause 
heavy  or  excessive  precipitation. 

The  low  pressure  areas  that  are  first  seen  over  the  southern 
plains,  and  those  that  move  into  the  Southern  States  from  the  Gulf 
of  Mexico  generally  drift  northeastward  and  pass  off  the  north 
Atlantic  coast.  They  are  usually  more  intense  and  energetic  than 
the  disturbances  that  cross  the  country  along  the  northern  border 
because  they  move  through  moister  and  warmer  regions. 

A  well-developed  storm  central  over  northern  Texas  and  drifting 
toward  the  New  England  States  is  drawing  warm  air  currents 
heavily  laden  with  moisture  from  the  Gulf  of  Mexico,  during  the 
entire  time  that  it  is  crossing  the  great  central  valleys.  The  rainfall 
attending  such  storms  is  generally  heavy.  As  these  storms  move 
farther  northeastward,  they  pass  between  the  Great  Lakes  and  the 
Atlantic  coast,  and  the  decreasing  supply  of  moisture  from  the  Gulf 
is  replenished  from  these  other  sources  and  heavy  rains  may  and 
generally  do  continue. 

The  storms  that  move  up  f  om  the  Tropics  to  the  South  Atlantic 
or  Gulf  coasts  of  the  United  States  during  the  late  summer  or  early 
autumn  are  termed  *  'hurricanes."  They  are  usually  smaller  in 
area  than  the  storms  which  form  on  the  continent,  but  are  more 
intense  and  energetic.  When  first  observed  in  the  Tropics,  they 
have  a  tendency  to  move  slowly  northwestward,  and  to  continue 
in  that  direction  until  they  reach  the  latitude  of  the  Gulf  coast, 
when  they  recurve  to  the  northeast  unless  prevented  from  doing 
so  by  an  area  of  high  barometric  pressure.  On  recurving  they  usually 
increase  their  rate  of  movement  and  sometimes  sweep  over  the  en- 
tire Atlantic  coast  in  less  than  48  hours. 

When  a  hurricane  makes  its  appearance  in  southern  waters  it  is 
necessary  to  receive  frequent  reports  from  all  observation  points 
in  its  vicinity  and  watch  its  movements  very  closely  in  order  to 
issue  warnings  ahead  of  it. 

Cold  waves,  (Fig.  426)  usually  accompany  energetic  areas  of 
high  barometric  pressure  following  those  of  low  pressure.  They  are 
confined  principally  to  the  winter  months,  when  temperature  changes 
are  more  sudden  and  pronounced. 

During  the  winter  season,  if  a  high  pressure  area  appears  in  the 
far  northwest,  with  a  low  area  over  the  southern  states,  the  low 
area  will  usually  move  eastward  and  northeastward,  while  the 
high  area,  with  its  attendant  low  temperatures  will  sweep  south- 
ward to  the  Gulf  Coast.  Should  there  be  no  well-defined  area  of 
low  pressure  over  the  Southern  States,  the  high  area  would  be  more 
apt  to  pass  eastward  over  the  northerly  route.  A  high-pressure 
area  that  is  not  preceded  by  a  low  will  not  cause  so  great  a  fall  in 
temperature  in  proportion  to  its  intensity  as  one  that  is  thus 
preceded. 

[  760  ] 


METEOROLOGICAL  DATA 


Sec.  11 


[761] 


Sec.  11  METEOROLOGICAL  DATA 

The  high-pressure  areas  that  move  from  the  Northwest  into  the 
Southern  States  usually  decrease  in  energy  on  recurving  to  the 
eastward  or  northeastward,  and  so  reach  the  Atlantic  States  in  a 
modified  form  that  seldom  causes  a  marked  fall  in  temperature. 
When  cold  waves  occur  in  the  North  Atlantic  and  New  England 
States  they  follow  closely  upon  the  passage  of  a  center  of  low 
pressure,  the  high-pressure  area  generally  moving  eastward  or 
southeastward  from  the  upper  Lake  region.  Under  certain  condi- 
tions a  cold  wave  may  occur  at  the  rear  of  a  center  of  low  pressure, 
with  no  well-defined  high-pressure  area  following  it,  but  in  any 
event  an  increase  in  barometric  pressure  accompanies  every  cold 
wave. 

When  a  cold  area  of  high  pressure  is  following  a  low  from  tho 
Northwest  the  temperature  will  begin  to  fall  at  any  given  place  in 
its  track  as  soon  as  the  center  of  the  low  has  passed  eastward  far 
enough  to  bring  that  place  within  the  flow  of  air  between  the  two 
centers. 

Excessive  heat  is  caused  by  barometric  pressure  gradients  being 
practically  the  reverse  of  those  in  a  cold  wave,  the  high  pressure 
being  in  the  Southeast  and  the  low  pressure  in  the  Northwest. 
During  the  summer  season  an  area  of  only  moderately  high  baro- 
metric pressure  will  sometimes  stagnate  over  the  South  Atlantic 
States  or  just  off  the  coast,  while  a  low  moves  into  the  upper  Mis- 
sissippi Valley  and  the  upper  Lake  region.  Under  such  conditions 
the  air  currents  that  flow  from  the  central  portion  of  the  high  area 
toward  the  low  move  along  the  surface  and,  steadily  increasing  in 
temperature,  they  gather  up  moisture  over  their  course  and  cause 
abnormally  warm  and  humid  conditions  in  the  Ohio  Basin  and  in 
the  Middle  and  North  Atlantic  States.  If  the  areas  are  large,  with 
the  crest  of  high  pressure  off  the  south  Atlantic  Coast  and  the  center 
of  the  low  in  the  far  Northwest,  the  abnormally  high  temperatures 
will  cover  all  the  great  central  valleys. 

The  month  of  July  1901,  marked  the  most  intense  period  of  ab- 
normal heat  from  the  Atlantic  coast  westward  to  the  Rocky  Moun- 
tains that  has  been  recorded  in  the  United  States.  The  averagi- 
barometric  pressure  for  the  month  serves  to  illustrate  the  conditions 
that  caused  the  intense  heat  much  better  than  a  map  for  any  specific 
date,  and  a  chart  showing  the  average  pressure  for  that  period  has 
been  taken  from  the  monthly  Weather  Review  and  adapted  to  this 
purpose.  (Fig.  427.) 

In  the  Northern  States  much  the  greater  portion  of  the  rainfall 
occurs  on  the  eastern  and  southern  sides  of  low-pressure  areas. 
The  heaviest  rains  in  the  Southern  States  are  usually  caused  by 
low-pressure  areas  moving  in  from  the  Gulf,  but  rain  often  occurs 
when  an  area  of  high  pressure  moves  down  from  the  north,  the  cool 
descending  air  currents  appearing  to  run  under  the  moist  lower  air 
strata  which  are  raised,  cooled  by  expansion,  and  a  portion  of  their 
moisture  condensed  and  precipitated. 

The  areas  of  high  and  low  barometric  pressure  are  more  energetic 
excepting  the  West  Indian  Hurricanes,  and  move  across  the  country 

[  762  ] 


METEOROLOGICAL  DATA 


Sec.  11 


[  763  ] 


Sec.  11  METEOROLOGICAL  DATA 

at  a  more  rapid  rate  during  the  winter  than  during  the  summer 
season.  The  rate  of  movement  of  a  storm  area  across  the  country 
should  not  be  confused  with  the  wind  velocities  within  its  boundaries, 
for  sometimes  a  storm  that  is  moving  quite  rapidly  will  be  suddenly 
checked  and  will  increase  in  energy  as  a  consequence,  thus  develop- 
ing higher  wind  velocities  than  when  its  movement  of  translation  was 
greater.  The  West  Indian  hurricanes  travel  very  slowly  so  long 
as  they  follow  the  westerly  course,  but  the  wind  velocities  generated 
within  them  are  usually  destructive. 

The  rate  of  movement  of  storm  areas  is  seldom  steady  and  uniform 
for  any  considerable  length  of  time,  but  the  average  rate  is  about 
37  miles  per  hour  in  whiter  and  22  miles  per  hour  in  summer. 
They  travel  faster  across  the  Northern  States  than  they  do  in  the 
southern  portion  of  the  country. 

High  pressure  areas  have  a  greater  tendency  to  turn  southward 
while  crossing  the  great  central  valleys  in  the  winter  than  they  have 
during  the  summer.  The  larger  and  better  formed  all  atmospheric 
disturbances  are,  the  easier  it  becomes  to  anticipate  their  movements 
and  developments  and  thereby  to  forecast  ahead  of  them.  It  is 
when  a  map  shows  several  partly  developed  areas,  or  when  their 
movements  become  sluggish,  that  forecasting  becomes  most  difficult. 

During  the  midsummer  when  the  pressure  formations  are  least 
energetic  there  is  a  tendency  for  conditions  to  become  localized, 
and  we  have  showers  instead  of  general  rains.  When  conditions 
indicate  showers  a  forecast  must  be  made  of  them,  and  while  they 
may  cover  much  the  greater  portion  of  the  territory  for  which  they 
are  forecast,  still  there  will  be  many  places  where  no  rain  will  occur. 

When  conditions  are  such  as  to  indicate  only  a  few  widely  scat- 
tered showers,  fair  weather  will  no  doubt  prevail  over  three-fourths 
of  the  territory  covered  by  the  forecast. 

5.  THE  THUNDERSTORM.*     In  a  thunderstorm,  the  thunder 
and  lightning  constitute  no  essential  part  of  the  storm  in  the  sense 
of  being  the  cause  or  the  maintaining  factors  of  it,  but  are  rather  the 
result  of  the  conditions  within  the  storm. 

6.  Phenomena  of  Lightning.     The  source,  or  cause,  of  atmos- 
pheric electricity  remained  a  mystery  until  a  few  years  ago  when  the 
experiments  of  Simpson  an  English  scientist,  shed  much  light  upon 
the  subject.     He  experimented  in  the  laboratory  with  blasts  of  air 
directed  against  drops  of  distilled  water,  the  force  of  the  blast  being 
great  enough  to  break  the  drops  up  into  a  spray.     The  spray  was 
negatively    electrified,    while   the   larger   drops   left   behind    were 
positively  electrified.     He  further  devised  a  clever  combination  of 
recording  devices  which  automatically  measured  the  quantity  of 
rainfall  together  with  the  amount  and  kind  of  electricity  brought 
down  by  the  rain.     Experiments   conducted  in   India  with   this 
device  showed  that  two  or  three  times  as  much  positive  as  negative 

*From  a  lecture  delivered  by  Dr.  William  J.  Humphreys  to  the  Philadelphia 
Electric  Co.  Section  of  the  N.  E.  L.  A. 

[764] 


METEOROLOGICAL  DATA  Sec.  11 

electricity  is  brought  down  by  the  thunderstorm  rain.  Both  experi- 
ments have  since  been  repeated  in  nearly  every  country,  and  in 
every  instance  his  findings  have  been  confirmed.  The  results  of 
these  experiments  fit  in  nicely  with  the  known  conditions  in  thunder- 
storms and  furnish  a  reasonable  explanation  of  the  phenomena  of 
lightning.  In  a  thunderstorm  the  uprush  of  air  is  violent  at  times, 
as  is  evidenced  by  lumps  of  hail  that  can  only  be  formed  by  the 
carrying  of  raindrops  to  very  high  altitudes.  When  moisture 
particles  coalesce  into  large  drops  and  are  then  blown  into  a  spray 
by  the  strong  uprushing  air  currents,  the  laboratory  experiment  of 
electrical  separation  is  duplicated.  The  spray  which  is  negatively 
electrified  is  carried  aloft  while  the  larger  drops  left  behind,  and 
which  are  positively  electrified,  fall  to  earth,  thus  explaining  why 
such  a  large  portion  of  positive  electricity  is  brought  down  by  rain. 

7.  Causes  of  the  Strong  Uprushing  Air  Currents.     It  has  been 
found  that,  starting  from  the  surface  of  the  earth,  the  temperature 
decreases  rather  steadily  to  an  elevation  of  from  30,000  to  40,000 
feet  above  sea  level.     If  a  body  of  air  at  the  earth's  surface  should 
be    carried   upward    its   temperature   would    decrease    practically 
uniformly,  the  loss  of  heat  being  due  to  the  work  of  expansion 
against  the  force  of  gravity.     The  heating  of  the  atmosphere,  as  it 
does  on  a  warm  summer  afternoon,  causes  it  to  rise  by  convection 
until  it  reaches  an  altitude  where  cloud  begins  to  form.     Starting, 
for  example,  with  a  temperature  of  86°  Fahrenheit  and  a  relative 
humidity  of  15  per  cent,  clouds  will  form  at  an  altitude  of  about 
5000  feet,  the  temperature  of  the  rising  air  having  fallen  to  59°. 
As  soon  as  cloud  begins  to  form  latent  heat  is  freed  and  decreases 
the  rate  of  cooling  so  that  the  air  within  the  cloud  becomes  warmer 
than  the  surrounding  air.     Being  warmer  it  is  less  dense  and  is 
forced  upward  by  the  heavier  air  around  it.     The  more  rapid  the 
condensation,  and  the  consequent  freeing  of  latent  heat,  the  greater 
will  be  the  temperature  difference  between  the  air  in  the  cloud  and 
of  that  surrounding  it,  and  the  stronger  will  be  the  resulting  uprush 
of  the  air  within  the  cumulus  cloud.     The  formation  of  a  cumulus 
cloud,  (Fig.  428)  with  its  piles  upon  piles  of  cauliflower  like  heads, 
is  a  visible  demonstration  of  the  action  that  is  taking  place  within. 

8.  Time  and  Localities  Favoring  Thunderstorms.     The  formation 
of  a  thunderstorm  requires  first  of  all  enough  heat  to  cause  rising 
convective  air  currents  to  the  altitude  where  condensation  begins, 
and  second  a  moist  air  which  will  favor  rapid  condensation. ^    In 
consequence  they  are  most  frequent  in  moist  equatorial  regions, 
and  least  frequent  in  the  cooler  regions  of  the  north  and  over  large 
dry  plains    or  deserts.     They  are  more  frequent  during  afternoons 
than  during  the  morning  hours  over  the  land,  while  over  the  ocean 
they  are  most  frequent  at  night,  because  the  temperature  conditions 
at  those  times  favor  vertical  convection.     Thunderstorms  are  most 
frequent  over  the  land  in  summer,  when  the  amount  of  heat  received 
is  greatest,  while  over  the  ocean  they  are  most  frequent  in  winter, 

[  765  ] 


Sec.  11 


METEOROLOGICAL  DATA 


since  the  temperature  of  the  ocean  does  not  vary  greatly  from  winter 
to  summer  while  the  air  blowing  over  it  from  the  land  does  do  so 
and  thus  causes  the  temperature  gradients  that  bring  about  rapid 
vertical  convection. 

9.  RAIN.*  When  moisture  laden  air  rises  into  strata  that  are 
less  dense  it  expands.  The  work  of  expansion,  against  the  force 
of  gravity,  consumes  heat,  thus  lowering  its  temperature  and  lessen- 
ing its  capacity  for  moisture.  The  lessening  of  air  density  does  not 
materially  affect  its  capacity  for  moisture  except  insofar  as  it  reduces 
the  temperature.  This  would  indicate  that  the  atmospheric  gases 
do  not  absorb  the  water  vapor,  but  that  the  vapor  diffuses  through 
the  space  nearly  independent  of  the  atmospheric  gases,  and  con- 
trolled mainly  by  the  temperature.  When  cooling  continues  to 
the  point  of  saturation  then  condensation  begins  and  cloud  is 


FIG.  428. — Cumulus  cloud. 

formed.  The  first  visible  moisture  particles  may  be  supported  by 
the  rising  air  currents,  but  if  condensation  be  continued  long  enough 
and  rapidly  enough,  the  drops  will  coalesce  and  become  large  and 
heavy  enough  to  fall  through  the  rising  air  currents  and  reach  the 
earth  as  rain.  Dust  particles  usually  act  as  the  nuclei  of  condensa- 
tion, but  it  has  been  shown  that  ionized  air  may  act  in  that  capacity, 
and  that  it  probably  does  to  some  extent.  If  saturated  air  bo 
cooled  20°  F.  it  will  lose  pratically  one-half  of  its  moisture,  this 
being  true  within  the  range  of  temperatures  ordinarily  experienced 
in  the  free  air. 

10.  SNOW.*  When  condensation  is  rapid  enough  to  cause  pre- 
cipitation while  the  temperature  is  below  the  freezing  point,  snow- 
flakes  are  formed  instead  of  raindrops. 

*  Information  supplied  by  Mr.  Geo.  S.  Bliss,  U.  S.  Dept.  of  Agriculture,  Weather 
Bureau. 

.[766.] 


METEOROLOGICAL  DATA  Sec.  11 

11.  HAIL.*     Hail  rarely  occurs  except  as  an  accompaniment  of  a 
thunderstorm,  and  in  which  the  vertical  air  currents  are  very  strong. 
The  raindrops  are  carried  by  these  vertical  air  currents  up  into  air 
strata  in  which  the  temperature  is  below  the  freezing  point,  then  fall 
back  into  the  cloud,  become  coated  with  moisture,  and  are  again 
carried  up  into  the  cold  air  strata.     This  process  may  be  repeated 
several  times  when  the  vertical  currents  are  unusually  strong,  and 
the  hailstone  may  build  up  its  concentric  layers  until  it  becomes 
quite  large. 

12.  ICE  STORMS.*    These  peculiar  phenomena,  popularly  called 
sleet  storms,  occur  under  conditions  that  are  known  to  meteorologists 
as  inversion  of  temperature,  that  is,  the  air  at  some  distance  above 
the  earth  is  wanner  than  at  the  surface.     After  a  more  or  less  pro- 
tracted cold  spell,  during  which  the  ground  has  become  frozen, 
and  the  walls  of  buildings  and  other  exposed  surfaces  are  cooled 
below  the  freezing  point,  the  air  at  some  distance  above  the  earth 
may  be  warmed  quite  rapidly  to  a  point  above  freezing,  while  that 
near  the  cold  surfaces  may  remain  at  or  slightly  below  freezing. 
If  precipitation  occurs  at  such  times  it  passes  through  the  warmer 
air  strata  as  rain,  but  is  frozen  on  coming  into  contact  with  the 
cold  surfaces,  thus  forming  a  coating  of  ice. 

13.  SLEET.*     Sleet,    properly  speaking,   is  frozen  rain  drops. 
It  usually  occurs  intermingled  with  rain,  but  may  fall  as  clear  ice 
pellets,  unmixed  with  rain.     These  pellets  should  not  be  confused 
with  hailstones  which  are  larger  and  are  made  up  of  concentric 
layers;   neither  should  they  be  confused  with  white,  opaque  pellets 
of  hard  snow. 

14.  DISCUSSION  OF  SLEET  DATA.     The  data  submitted  is 
necessarily  incomplete  in  so  far  as  the  amount  of  sleet  formation 
on  wires  is  concerned;   where  recorded  wind  velocities  and  temper- 
atures are  tabulated  they  represent  the  worst  conditions  that  gov- 
ernment records  show  for  that  particular  station   during   a  sleet 
storm. 

Much  higher  wind  velocities  and  lower  temperatures  are  recorded 
at  various  periods  during  the  year  at  these  stations,  but  they  did 
not  occur  during  a  sleet  storm. 

A  summary  of  the  data  obtained  follows: 

(1)  The  number  of  years  record  covers  a  period  of  from  five  (5) 
to  forty-three  (43)  years. 

(2)  The  maximum  recorded  wind  velocity  of  487  sleet  storms  was 
greater  than  40  miles  per  hour  in  31  instances  (6.36%);    greater 
than  50  miles  per  hour  in  12  instances  (2.46%);   and  greater  than 
60  miles  per  hour  in  five  (5)  instances  (1.03%). 

*  Information  supplied  by  Mr.  Geo.  S.  Bliss,  U.  S.  Dept.  of  Agriculture,  Weather 
Bureau. 

[767] 


Sec.  11 


METEOROLOGICAL  DATA 


TABLE  112 

MONTHLY  MEAN  MAXIMUM  TEMPERATURES 

Mean  Maximum  Monthly  Temperature  —  Averaged  for  the 
Number  of  Years  Recorded 

STATIONS 

1 

I 

2 

J 

1 
1 

I 

I 

2 

1 

ft 

•< 

£ 

| 

>-5 

>, 

3 

>-s 

3 
U 
3 
^ 

J 

S 

D 
| 

1 

S 

1 

| 
• 
0 

Y, 

1 
§ 

a 

Abilene,  Tex  
Albany,  N.  Y  

28 
40 
39 
10 
15 
42 
40 
43 
41 
39 
43 
39 
40 
40 
43 
31 
36 
27 
33 
25 
40 
36 
40 
40 
42 
38 
39 
41 
37 
17 
39 
26 
36 
41 
33 
17 
39 
40 
33 
24 
42 
26 
35 

56 
31 
26 
54 
39 
36 
31 
58 
31 
40 
33 
43 
31 
27 
18 
49 
56 
23 
23 
38 
47 
65 
48 
62 
37 
49 
35 
30 
39.3 
66 
38.7 
34 
47 
20 
37 
54 
39 
56 
33.2 
69 
41.4 
42 
17 

58 
32 
26 
56 
43 
36 
31 
59 
33 
42 
34 
44 
32 
30 
22 
51 
61 
25 
34 
38 
50 
66 
51 
64 
38 
50 
38 
34 
40.3 
68 
39.7 
33 
51 
24 
41 
58 
43 
59 
38.0 
70 
43.0 
43 
19 

68 
41 
34 
68 
52 
41 
38 
66 
42 
52 
42 
52 
41 
42 
32 
63 
68 
36 
38 
52 
59 
67 
61 
71 
45 
57 
49 
46 
48.3 
74 
48.8 
43 
57 
37 
51 
59 
52 
68 
49.0 
77 
51.5 
56 
33 

76 
55 
47 
73 
62 
54 
50 
72 
54 
63 
54 
60 
55 
59 
46 
72 
71 
52 
57 
65 
68 
70 
71 
76 
57 
65 
62 
62 
60.2 
82 
60.6 
58 
62 
56 
60 
62 
60 
76 
59.2 
80 
63.0 
68 
55 

83 
69 
59 
82 
69 
66 
62 
80 
65 
74 
66 
69 
67 
70 
57 
80 
80 
64 
65 
74 
78 
73 
79 
83 
68 
75 
70 
72 
71.5 
90 
72.9 
65 
68 
68 
68 
62 
68 
83 
67.5 
86 
74.4 
76 
56 

89 
78 
70 
88 
78 
75 
72 
86 
74 
82 
75 
80 
76 
79 
69 
87 
86 
76 
74 
83 
84 
78 
86 
87 
77 
83 
80 
81 
80.2 
100 
80.7 
76 
73 
77 
79 
64 
78 
90 
74.0 
89 
82.2 
85 
75 

91 
82 
75 
90 
88 
81 
76 
88 
80 
86 
79 
86 
81 
84 
74 
98 
88 
80 
82 
87 
87 
82 
89 
89 
82 
87 
86 
86 
84.7 
103 
84.6 
83 
81 
b2 
88 
64 
51 
92 
52.9 
89 
56.5 
0 
2 

92 
80 
73 
90 
86 
78 
76 
87 
78 
84 
77 
85 
79 
82 
71 
91 
88 
77 
80 
86 
86 
83 
88 
89 
80 
84 
85 
84 
S2.2 
101 
82.6 
83 
81 
80 
87 
54 
79 
92 
2.2 
59 
3.8 
0 
1 

86 
73 
66 
81 
76 
71 
70 
83 
72 
78 
72 
77 
72 
74 
64 
85 
85 
70 
69 
79 
81 
82 
32 
85 
74 
79 
77 
76 
76.3 
97 
76.8 
74 
74 
71 
76 
58 
73 
57 
71.1 
8 
7.9 
2 
0 

76 
60 
54 
75 
64 
61 
58 
74 
60 
66 
61 
65 
60 
61 
52 
74 
77 
57 
58 
68 
70 
77 
72 
78 
63 
69 
65 
64 
34.7 
35 
53.5 
61 
64 
57 
63 
67 
62 
77 
58.9 
82 
66.5 
70 
56 

65 
46 
40 
65 
52 
49 
45 
66 
46 
52 
47 
52 
45 
44 
36 
62 
69 
41 
40 
53 
58 
72 
60 
72 
51 
59 
50 
48 

5f 

30.7 

47 
54 
40 

50 

61 
ft 

.6 
14.4 
76 
53.9 
55 
37 

56 
36 
31 
54 
39 
39 
36 
59 
36 
43 
37 
45 
35 
32 
25 
52 
62 
29 
33 
42 
48 
67 
51 
63 
41 
50 
40 
36 

tl'1 

41.3 
40 
48 
27 
39 
56 
41 
58 
36.6 
70 
14.3 
45 
24 

Alpena,  Mich  

Birmingham,  Ala  
Boise,  Idaho  

Boston,  Mass  .  .  . 
Buffalo,  N.  Y.. 

Charleston,  S.  C  
Chicago,  111. 

Cincinnati,  Ohio  
Cleveland,  Ohio  
Denver,  Colo  
Detroit,  Mich  
Dubuque,  Iowa  

Duluth,  Minn  
Fort  Smith,  Ark  
Galveston,  Tex  

Green  Bay,  Wis  

Havre,  Mont  

Kansas  City,  Mo 

Knoxville,  Tenn  

Los  Angeles,  Cal  
Memphis,  Tenn  
New  Orleans,  La 

New  York,  N.  Y  
Norfolk,  Va.. 

North  Platte,  Neb  
Omaha,  Neb 

Philadelphia,  Pa  
Phoenix,  Ariz 

Pittsburg,  Pa  
Rapid  City,  S.  D  
Roseburg,  Ore  
St.  Paul,  Minn  

Salt  Lake  City,  Utah  
San  Francisco,  Cal  .... 

Santa  Fe,  N.  M  
Shreveport,  La  

Spokane,  Wash  

Tampa,  Fla 

Washington,  D.  C  

Wichita,  Kansas.  .  . 

WiUiston,  N.  D.. 

[768] 


METEOROLOGICAL  DATA 


Sec.  11 


TABLE  113 
MONTHLY  MEAN  MINIMUM  TEMPERATURES. 

Mean  Minimum  Monthly  Temperature  —  Averaged  for  the 
Number  of  Years  Recorded. 

STATIONS 

IB 

o 
£ 
£ 

1 

b 

a 

c3 
1-5 

b 

1 
£ 

j3 
1 

'C 
a 
<; 

jj 

^ 

1 
>-s 

_>, 
*9 
>•» 

\ 

•= 
< 

1 

1 

•t 

j 

| 

I 
& 

1 

% 
1 

Abilene,  Tex  

28 
40 
39 
10 
15 
42 
40 
43 
41 
39 
43 
39 
40 
40 
43 
31 
36 
27 
33 
25 
40 
36 
40 
40 
42 
38 
39 
41 
37 
17 
39 
26 
36 
41 
38 
17 
39 
40 
33 
24 
42 
26 
35 

34 
15 
12 
38 
26 
20 
19 
43 
17 
25 
20 
17 
18 
11 
1 
30 
45 
8 
2 
21 
30 
44 
34 
45 
24 
33 
11 
12 
25.7 
39 
23.6 
11 
35 
3 
22 
45 
19 
39 
21.1 
51 
25.8 
23 
-5 

35 
15 
9 
37 
27 
20 
17 
44 
19 
26 
20 
20 
18 
13 
4 
32 
50 
8 
4 
21 
32 
45 
36 
50 
24 
34 
16 
16 
25.9 
43 
24.3 
11 
36 
6 
26 
47 
22 
41 
23.1 
53 
26.6 
23 
-2 

45 
25 
17 
48 
34 
28 
25 
50 
28 
35 
28 
26 
26 
25 
15 
42 
58 
20 
16 
33 
40 
47 
45 
56 
31 
40 
23 
27 
32.9 
47 
31.3 
20 
38 
20 
33 
47 
29 
49 
30.7 
58 
33.8 
34 
12 

53 
37 
31 
53 
39 
38 
35 
57 
39 
45 
39 
35 
37 
39 
31 
51 
62 
34 
33 
46 
48 
49 
53 
61 
41 
48 
36 
41 
42.8 
52 
41.4 
34 
41 
36 
40 
49 
35 
56 
37.3 
61 
43.3 
45 
31 

61 
49 
41 
62 
45 
48 
46 
66 
49 
55 
50 
44 
49 
50 
40 
59 
71 
45 
41 
55 
56 
54 
62 
68 
52 
58 
47 
53 
53.5 
59 
52.4 
43 
45 
48 
46 
50 
43 
64 
44.5 
67 
54.0 
55 
41 

68 
58 
51 
68 
51 
58 
57 
72 
59 
65 
60 
52 
58 
59 
48 
67 
77 
55 
50 
64 
64 
56 
70 
74 
61 
66 
56 
62 
62.8 
69 
60.8 
53 
49 
58 
55 
51 
52 
70 
50.4 
71 
62.8 
64 
52 

72 
63 
57 
71 
58 
64 
63 
75 
66 
68 
64 
58 
63 
64 
56 
70 
79 
60 
54 
69 
68 
59 
73 
76 
67 
71 
61 
67 
68.1 
76 
65.0 
58 
53 
62 
63 
52 
57 
73 
55.1 
73 
67.6 
68 
54 

72 
61 
55 
71 
56 
62 
61 
75 
65 
66 
82 
57 
61 
62 
57 
70 
78 
58 
51 
68 
66 
60 
71 
76 
66 
70 
60 
65 
66.5 
76 
63.0 
57 
52 
60 
62 
53 
56 
72 
53.6 
74 
65.7 
67 
52 

65 
54 
49 
66 
48 
55 
55 
71 
58 
60 
56 
49 
55 
54 
49 
63 
75 
51 
43 
60 
61 
57 
65 
72 
60 
55 
50 
54 
60.4 
68 
57.3 
48 
48 
51 
52 
54 
50 
67 
45.8 
72 
59.0 
60 
41 

54 
43 
39 
54 
40 
45 
44 
60 
46 
48 
45 
37 
44 
42 
38 
51 
68 
41 
33 
48 
48 
53 
54 
63 
49 
54 
36 
44 
49.0 
56 
45.7 
37 
43 
40 
42 
53 
38 
56 
37.9 
66 
47.1 
48 
31 

43 
32 
29 
45 
34 
35 
33 
51 
33 
37 
34 
26 
33 
28 
23 
41 
58 
27 
19 
35 
38 
48 
43 
54 
38 
44 
23 
32 
38.7 
46 
35.7 
24 
40 
24 
32 
50 
28 
46 
31.2 
58 
36.6 
35 
16 

36 
21 
19 
37 
25 
25 
24 
44 
23 
29 
25 
20 
24 
18 
10 
33 
51 
17 
12 
26 
32 
46 
38 
48 
28 
36 
16 
19 
29.2 
38 
27.4 
18 
36 
12 
25 
46 
20 
11 
26.3 
52 
28.6 
26 
5 

Albany,  N.  Y  

Alpena,  Mich 

Birmingham,  Ala  

Boise,  Idaho 

Boston,  Mass  

Buffalo,  N.  Y  

Charleston,  S.  C  

Chicago,  111  
Cincinnati,  Ohio  
Cleveland,  Ohio  

Denver,  Colo 

Detroit,  Mich  
Dubuque   Iowa 

Duluth,  Minn  
Fort  Smith,  Ark  . 

Galveston,  Tex  

Green  Bay,  Wis  
Havre,  Mont 

Kansas  City,  Mo  
Knoxville,  Tenn 

Los  Angeles,  Cal  

Memphis,  Tenn  
New  Orleans,  La  
New  York,  N.  Y  

Norfolk   Va 

North  Platte,  Neb  
Omaha,  Neb 

Philadelphia,  Pa  
Phoenix,  Ariz  

Pittsburg  Pa 

Rapid  City,  S.  D  
Roseburg,  Ore  
St.  Paul,  Minn  
Salt  Lake  City,  Utah 

San  Francisco,  Cal.  .  . 

Santa  Fe,  N.  M  
Shreveport,  La  

Spokane,  Wash  

Tampa,  Fla  

Washington,  D.  C  
Wichita,  Kansas  

Williston,  N.  D  

[769] 


Sec.  11 


METEOROLOGICAL  DATA 


TABLE  114 

TOTAL  NUMBER  OF  DAYS  WITH  MAXIMUM 
TEMPERATURE  90°  OR  ABOVE. 


STATIONS 

Years  record 

a 

February 

I 

Hi; 

~ 

| 

i 

"3 

1 

September 

October  ' 

November 

December 

Abilene,  Tex   

27 
40 
39 
10 
15 
42 
43 
43 
43 
39 
43 
39 
40 
40 
43 
31 
40 
27 
30 
25 
39 
36 
40 
43 
42 
43 
39 
41 
43 
17 
39 
26 
36 
25 
38 
39 
37 
40 
24 
24 
43 
26 
32 

0 
0 
0 
0 
0 
0 
0 
0 
0 
0 

1 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 

0 
0 
0 
0 

24 
0 
0 
1 
0 
0 
0 
6 
0 
0 
0 
0 
0 
0 
0 
3 
0 
0 
0 
4 
0 
4 
0 
0 
0 
3 
0 
1 
0 
10 
0 
0 
0 
0 
0 
0 
0 
2 
0 
0 
3 
6 
0 

50 
0 
0 
0 
2 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
7 
0 
0 
1 
2 
2 
20 
0 
0 
0 
3 
5 
4 
4 
75 
0 
0 
0 
0 
0 
0 
0 
17 
0 
4 
5 
11 
4 

155 
18 
7 
14 
7 
10 
1 
51 
11 
22 
1 
9 
5 
18 
0 
45 
6 
2 
11 
11 
29 
22 
31 
42 
9 
46 
30 
23 
18 
27S 
43 
5 
9 
3 
5 
2 
0 
143 
4 
70 
65 
25 
18 

417 
53 
24 
86 
46 
67 
2 
233 
62 
164 
14 
192 
35 
113 
14 
294 
120 
43 
44 
132 
181 
50 
337 
384 
61 
180 
150 
168 
126 
480 
122 
65 
34 
50 
103 
13 
0 
652 
30 
254 
204 
195 
77 

652 
135 
44 
89 
223 
156 
17 
417 
166 
357 
37 
439 
108 
248 
41 
598 
236 
74 
178 
264 
345 
98 
553 
625 
136 
400 
371 
381 
242 
513 
279 
169 
148 
82 
472 
6 
8 
904 
155 
305 
417 
397 
176 

635 
63 
21 
123 
184 
56 
6 
275 

229 
20 
334 
59 
148 
13 
575 
223 
47 
149 
266 
257 
149 
424 
589 
54 
226 
365 
283 
100 
509 
183 
181 
122 
54 
371 
3 
29 
871 
152 
319 
233 
428 
182 

291 
18 
19 
65 
31 
21 
1 
58 
40 
102 
6 
56 
23 
51 
2 
296 
61 
36 
24 
117 
93 
100 
192 
232 
24 
65 
112 
124 
34 
450 
79 
69 
54 
31 
25 
20 
11 
444 
9 
196 
90 
198 
33 

41 
1 

0 
0 

1 

0 
0 
0 
42 
3 
0 
0 
4 
11 
75 
6 
12 
0 
0 
5 
2 
0 
150 
3 
1 
6 
0 
0 
5 
0 
58 
0 
15 
3 
8 
2 

0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
29 
0 
0 
0 
0 
0 
0 
0 
5 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 

0 
0 
0 

0 
0 
0 
.   0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 

Albany  N  Y 

Alpena,  Mich  

Birmingham,  Ala  
Boise,  Idaho  

Buffalo,  N.  Y  
Charleston  S  C 

Chicago,  111  

Cleveland,  Ohio  
Denver,  Colo  

Detroit,  Mich  
Dubuque,  Iowa  

Duluth,  Minn  
Fort  Smith,  Ark  

Galveston,  Tex  
Green  Bay,  Wis  

Havre,  Mont  
Kansas  City,  Mo  

Knoxville,  Tenn  
Los  Angeles,  Cal  

Memphis,  Tenn  
New  Orleans,  La  

New  York,  N.  Y  
Norfolk,  Va  

North  Platte,  Neb  
Omaha,  Neb  

Philadelphia,  Pa  
Phoenix,  Ariz 

Pittsburg,  Pa  
Rapid  City,  S  D 

Roseburg,  Ore  
St.  Paul,  Minn 

Salt  Lake  City,  Utah  
San  Francisco,  Cal  
Santa  Fe,  N.  M  

Shreveport,  La     .... 

Spokane,  Wash  

Tampa,  Fla  

Washington,  D.  C 

Wichita,  Kansas  

Williston,  N.  D  

[  770] 


METEOROLOGICAL  DATA 


Sec.  11 


TABLE  115 

TOTAL  NUMBER  OF  DAYS  WITH  MINIMUM 

TEMPERATURE  ZERO  OR  BELOW. 

1 

£ 

, 

b 

1 

1 

j§ 

STATIONS 

£ 

as 

c3 
3 

^ 

^ 

1 

1 

a 

o3 

3 

£ 

J3 

I 

T, 

tf 

8 

>> 

M 

p 

3 

> 

s 

£ 

93 
1-5 

& 

% 

ft 
«< 

tl 

3 

t-B 

"3 

H^ 

3 

•< 

I* 

0 

I 

I 

Abilene,  Tex  .  . 
Albany,  N.  Y  

27 
40 

3 

148 

4 
150 

0 

14 

0 
0 

0 
0 

0 

0 

0 

0 

0 

0 

0 
62 

Alpena,  Mich.  
Birmingham,  Ala  
Boise\  Idaho  

39 
10 
15 

201 
0 
11 

273 

1 
5 

113 
0 
0 

0 
0 

0 
0 

0 
0 

0 
0 

0 
0 

0 
0 
0 

3 
0 

0 

41 
0 
0 

Boston,  Mass  
Buffalo,  N.  Y  

42 
43 

48 
55 

40 
86 

4 

0 

0 

0 

0 

1 
0 

24 
11 

Charleston,  S.  C  

43 

0 

0 

0 

0 

0 

0 

0 

0 

0 

Chicago,  111  

41 

172 

121 

10 

0 

0 

0 

0 

6 

67 

Cincinnati,  Ohio  

38 

36 

27 

0 

0 

0 

0 

0 

0 

15 

Cleveland,  Ohio  

43 

55 

37 

5 

0 

0 

0 

0 

1 

15 

Denver,  Colo 

39 

156 

114 

20 

o 

0 

0 

0 

22 

95 

Detroit,  Mich  

40 

Aft 

77 

Q7A 

93 

OOA 

5 

«)4 

0 

0 

0 

0 

1 

10 

21 

1  £1 

DUDUQUG,  Iowa  
Duluth,  Minn  

4U 

43 

36*± 

616 

ZoU 
453 

mm 

165 

0 

0 

0 

0 

0 

11 
63 

131 

321 

Fort  Smith,  Ark  

31 

11 

6 

0 

0 

0 

0 

0 

0 

0 

0 

Galveston,  Tex           

43 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

Green  Bay,  Wis  
Havre,  Mont 

27 
9 

238 
142 

215 
104 

51 
49 

0 
1 

0 
0 

0 

0 

0 

24 

97 
61 

Kansas  City,  Mo  

25 

A1 

52 

17 

51 

0 

0 

0 

0 

0 

0 

0 

13 

Knoxville,  Tenn  
Los  Angeles,  Cal  

41 

38 

AF\ 

H 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

Memphis,  Tenn  
New  Orleans,  La  

w 

43 

0 

0 

0 

0 

0 

0 

0 

0 

0 
0 

New  York,  N.  Y  

42 

6 

7 

0 

0 

0 

0 

0 

0 

4 

Norfolk,  Va  

43 

0 

0 

0 

0 

0 

0 

0 

0 

0 

North  Platte,  Neb  

39 

235 

183 

42 

0 

0 

0 

0 

30 

117 

Omaha,  Neb  

41 

307 

188 

16 

0 

0 

0 

0 

12 

133 

Philadelphia,  Pa 

43 

10 

11 

0 

0 

0 

0 

o 

2 

Phoenix,  Ariz  

17 

0 

0 

0 

0 

0 

0 

0 

0 

0 

Pittsburg,  Pa  
Rapid  City,  S.  D  

39 
26 

48 
212 

47 
202 

0 

71 

0 

1 

0 
0 

0 
0 

0 
0 

0 
0 

0 

27 

14 
86 

Roseburg,  Ore  

36 

3 

0 

0 

0 

0 

0 

0 

0 

0 

St.  Paul,  Minn  

41 

553 

416 

97 

0 

0 

0 

0 

63 

250 

Salt  Lake  City,  Utah  

38 

20 

13 

1 

0 

0 

0 

3 

41 

San  Francisco,  Cal  

Gnn4rk    T?£     AT     AT 

39 

QfT 

0 

OC 

0 

1Q 

0 

0 

0 

0 

0 

0 

0 

oanta  r  e,  IN  .  M  
Shreveport,  La  

O  1 

40 

«$*) 

0 

1" 

2 

0 

0 

0 

0 

0 

20 
0 

Spokane  Wash 

25 

35 

22 

0 

0 

0 

0 

2 

Tampa,  Fla  

24 

0 

0 

0 

0 

0 

0 

0 

Washington,  D.  C  

43 

16 

8 

0 

0 

0 

0 

2 

Wichita   Kansas 

26 

37 

36 

0 

0 

0 

0 

6 

Williston,  N.  D  

32 

589 

494 

258 

5 

0 

0 

0 

1 

132 

335 

[771] 


Sec.  11 


METEOROLOGICAL  DATA 


TABLE  116 

HIGHEST  WIND  VELOCITIES  ON  RECORD, 

WITH  DIRECTION. 

(The  recorded  velocities  as  given  are  the  greatest  maintained  for 

any  five  minute  period.) 

STATIONS. 

1 

i 

j 

4 

i 

§ 

J2 

83 

1 

• 

8H 

4 

£ 

* 

•< 

% 

Abilene.  Tex..  . 

27 

60W 

61W 

50SW 

60SW 

66SW 

Albany,  N.  Y  

40 

60NW 

70W 

54  NW 

48NW 

41NW 

Alpena,  Mich  

39 

56SE 

52SE 

55W 

52W 

478 

Birmingham,  Ala  

10 

50SE 

43SE 

40SE 

45S 

44SE 

Boise,  Idaho  

15 

38NW 

33NW 

38NW 

40SE 

42SW 

Boston,  Mass  .  .  . 

41 

64NE 

60E 

728 

60NE 

48E 

Buffalo,  N.  Y  

42 

90SW 

76SW 

90W 

75SW 

61SW 

Charleston,  S.  C  

43 

44SW 

56SE 

55NE 

67SE 

53NE 

Chicago,  111  

24 

66NE 

84NE 

68NE 

72NE 

72SW 

Cincinnati,  Ohio  

40 

48SW 

41NW 

48SW 

44SW 

45N 

Cleveland,  Ohio  

43 

72W 

65W 

68W 

66W 

60NW 

Denver,  C  clo 

41 

66  SW 

64W 

61NW 

60NW 

68NW 

Detroit,  Mich  

43 

60W 

60SW 

86W 

72NE 

74SW 

Dubuque,  Iowa  

40 

38NW 

36NW 

42SW 

39NW 

34NW 

Duluth,  Minn  

43 

71NW 

60NE 

62NE 

70NW 

60NE 

Fort  Smith,  Ark 

31 

66W 

54W 

56SW 

56SW 

54S 

Galveston,  Tex  

42 

62N 

59N 

61N 

52N 

60NW 

Green  Bay,  Wis  

27 

47NE 

55N 

48NW-SW 

46NE 

68N 

Havre,  Mont  

33 

60SW 

72NW 

60W 

63W 

63NW 

Kansas  City,  Mo  

25 

74NW 

53NW 

58SW 

56  NW 

52NW 

Knoxville,  Tenn  

41 

58SW 

60SW 

84S 

70W 

50SW 

Los  Angeles,  Cal  
Memphis,  Tenn  

36 
40 

48NE 
64W 

42NW 
58W 

46SW 
75SW 

42W 
64NW 

36W 
60NW 

New  Orleans,  La  

41 

42NW 

52SE 

45SW 

48N 

48NW 

New  York,  N.  Y  

30 

86SW 

96SW 

SON 

84NW 

64NW 

Norfolk,  Va  

42 

64SW 

59NW 

58SW 

55N 

62N 

Northplatte,  Neb  

39 

58NW 

68NW 

66NW 

96SE 

84SE 

Omaha,  Neb  

41 

66NW 

49NW 

52NW 

52NW 

50 

Philadelphia,  Pa  
Phoenix,  Ariz  

43 
17 

52-ENW 
SON 

48NE-NW 
32W 

60NW 
36SW 

50W 

34W 

60NW 

33SW 

Pittsburg,  Pa  
Rapid  City,  S.  D  

II 

26 

66W 
51W 

58W 
52N 

67W 
66SW 

68W 
63SW 

57NW 
56W 

Roseburg,  Ore  

36 

30SW 

36SW 

42W 

36SW 

30SW 

St.  Paul,  Minn  

25 

54N 

45NW 

60NW 

50NW 

52SW 

Salt  Lake  City,  Utah.. 
San  Francisco,  Cal.... 

38 
42 

60N 

57SE 

60N 
49S 

60NW 
60S 

60N-SW 

42SE 

56W 

45W 

Santa  Fe.N.M  

40 

44NW 

47W 

50E 

51SW 

51SW 

Shreveport,  N.  M  

42 

40NW-N 

39SE 

54NW 

44W 

52SE 

Spokane,  Wash  

33 

40SW 

41SW 

44SW 

40SW 

38SW-W 

Tampa,  Fla  

24 

40W 

49S 

41SW 

42SW 

42SE 

Washington,  D.  C  

43 

48NW 

60 

50NW 

43NW 

54SW 

Wichita,  Kansas  

26 

62NW 

49N 

60S 

54SE 

56SW 

Williston,  N.  D  

32 

66NW 

72NW 

60NW-N 

66NW 

66E 

[  772  ] 


METEOROLOGICAL  DATA 


Sec.  11 


TABLE  116  —  Continued 

HIGHEST  WIND  VELOCITIES  ON  RECORD, 

WITH  DIRECTION. 

(The  recorded  velocities  as  given  are  the  greatest  maintained  for 

any  five  minute  period.) 

i 

Jl 

kj 

I* 

2 

3 

& 

J 

1 

J 

tc. 

9 

- 

£ 

* 

o 
55 

27 

62NE 

60SE 

48NW 

42SW 

40NW 

48NE 

60W 

40 

48NW 

70W 

44SE 

39SE 

70E 

52SE 

70W-E 

39 

48W 

60SW 

41NW 

51SE 

52E 

50NW 

46NW 

10 

393 

45SE 

58NE 

50SE 

33SE 

39SE 

483 

15 

55SW 

41NE 

34NE 

40W 

48NW 

43W 

38W 

41 

41E 

60SW 

483 

60N 

54NE 

65W 

60E 

42 

72NW 

66SW 

60SW 

78W 

75SW 

SOW 

78W 

43 

54E 

483 

106SE 

623 

64N 

46E 

50SE 

24 

72NW 

72W 

72SW 

72SW 

63SE 

763 

72SW 

40 

52NW 

43SW 

50NW 

40NW 

41SW 

48SW 

40NW 

43 

64SW 

66NW 

58W 

66NW 

62W 

733 

613 

41 

603E 

55NE 

75NE 

51N 

553 

60NW 

56 

43 

69NW 

60W-SW 

60NW 

68NW 

61NW 

76SW 

56SW      • 

40 

60NW 

56NW 

45NE 

42NW 

36NW 

42  NW 

42NW 

43 

63NE 

56NW 

51NW 

18NE 

58NW 

70NW 

65NW 

31 

743 

49NW 

64W 

52W 

46NW 

55NW 

43W 

42 

54SE 

68E 

53NE 

84NE 

62NW 

54NW 

54N 

27 

59W 

59NW 

45NW 

52NW 

52NE 

54N-SW 

48SW-N 

33 

76NW 

59W 

60SW 

56SW 

60SW 

60NW 

60NW 

25 

67N 

57NW 

55NW 

48SW 

453 

50NW 

46NW 

41 

52W 

SON 

70NW 

60SW 

36SE 

60 

54SW 

36 

34SW 

25W 

24NE 

383 

34NE 

43NE 

38NW 

40 

60NW 

54W 

59NW 

60NW 

72SW 

60SW 

56SW 

41 

SON 

52E 

60E 

66SE 

54N 

42N 

48N 

30 

72NW 

72NW 

76NW 

72SW 

76NW 

76W 

85NW 

42 

49W 

60N 

60NE 

55SE 

60SW 

50NW 

58NW 

39 

90SW 

84W 

66NW 

72W 

623 

62NW 

72NW 

41 

60NW 

64NE 

54NE 

54NE 

43NW 

51NW 

50NW 

43 

54NW 

53N 

55NE 

58NW 

75SE 

60E 

63SE 

17 

32NW 

48SE 

40E 

38W 

36SE 

26W 

30SW 

41 

58NW 

52NW 

55NW 

44SW 

60NW 

50W 

69W 

26 

59SW 

60N 

60SW 

48NW 

46W 

60NW 

56SW 

36 

28SW 

28SW 

41NE 

30SW 

28SW 

30NE-SW 

48SW 

25 

64NW 

62N 

102NW 

55SE 

55W 

52N 

48N-NW 

38 

54NW 

50E 

64W 

44E 

52NE 

66NW 

50NW 

42 

48SW 

41W 

42SW 

40W 

44NE 

64NE 

60SE 

40 

48NW 

45W 

40E 

46N 

53SE 

51SE 

40NE 

42 

46N 

563 

43NE 

38W 

60NW 

54NW 

52W 

33 

48SW 

52W 

39SE-SW 

48W 

40SW 

42SW 

48SW 

24 

44SW 

433E 

34SE 

48NE 

48N 

363 

403 

43 

51NW 

68NE 

53N 

663E 

51NW 

54SW 

49 

26 

463 

56NW 

48NW 

47W 

483 

533 

453 

32 

63NW 

54NW-N 

67W 

60NW 

60NW-N 

60NW 

60NW-W 

[  773  ] 


Sec.  11 


METEOROLOGICAL  DATA 


TABLE  117 

TOTAL  NUMBER  OF  DAYS  WITH  MAXIMUM  RECORDED 
VELOCITY  OF  40  MILES  PER  HOUR  OR  MORE. 

STATIONS 

'H 

o 

6 

o> 

^ 

b 

03 
3 

1 

>j 

L 

c3 

1 

^ 
£ 
• 

^ 

a 
< 

| 

§ 
I-B 

>. 

3 

1 
M 

•3 
< 

1 
I 

1 

| 

5 

fc 

1 

QJ 

& 

Abilene,  Tex  

27 
33 
39 
10 

15 

22 
23 
24 
40 
43 
22 
23 
40 
43 
20 
22 
27 
22 
25 
22 
36 
24 
21 
22 
32 
39 
41 
43 
17 
41 
26 
36 
22 
22 

20 
5 
18 
1 
0 

191 
4 
92 

30 
6 

15 
4 
0 

14S 
17 
107 

30 
6 
26 
3 
0 

138 
11 
148 

38 
1 
26 
1 

25 
1 
9 
1 

18 

7 

7 

3 

2 

9 

12 

Albany,  N.  Y  
Alpena,  Mich 

7 
0 

5 
1 

3 

1 

9 
2 

1 

58 
12 
55 
1 
42 
11 
10 
1 
23 
5 
7 
6 
20 
4 
2 
0 
2 
5 
36 
3 
7 
4 

8 
0 

1 

91 
15 
85 
3 
75 
16 
23 
0 
33 
3 
11 
18 
12 
7 
0 
0 
4 
8 
79 
10 
14 
5 
10 
0 
10 
6 
0 
12 
9 

15 
0 
1 

182 
2 
126 
2 
122 
27 
39 
1 
54 
6 
14 
21 
19 
11 
6 
2 
12 
1 
110 
14 
14 
7 
15 
0 
15 
19 
0 
12 
8 
0 

16 
2 
0 

213 
5 
107 
1 
99 
30 
29 
1 
61 
3 
25 
12 
37 
10 
10 
0 
11 
4 
128 
13 
6 
10 
19 
0 
28 
13 
2 
14 
10 
1 
2 
2 
5 
2 
6 
4 
38 

Birmingham,  Ala  
Boise,  Idaho  
Boston,  Mass  

62 
14 
155 

No 
60 
9 
116 

Da 
26 
9 
61 

ta. 
39 
3 
59 

40 
15 
37 
3 
16 
14 
4 
2 
11 
6 
3 
8 
12 
12 
12 
0 
10 

Buffalo,  N  Y 

Charleston,  S.  C  
Chicago,  111  
Cincinnati,  Ohio  
Cleveland  Ohio 

124 
29 
33 
0 
72 
11 
21 
18 
29 
9 
11 
2 
22 

113 
21 
34 
0 
60 
18 
22 
19 
16 
19 
15 
1 
29 

111 
38 
46 
2 
64 
25 
16 
22 
19 
28 
20 
1 
28 

85 
33 
52 
0 
52 
21 
21 
35 
20 
27 
10 
1 
30 

57 
29 
26 
0 
46 
19 
20 
26 
20 
22 
5 
0 
16 

39 
14 
15 
2 
21 
16 
8 
10 
20 
13 
8 
0 
25 

46 
21 
21 
2 
17 
9 
3 
21 
27 
14 
5 
0 
10 

Denver,  Colo  
Detroit  Mich 

Dubuque,  Iowa  
Duluth,  Minn  
Fort  Smith,  Ark  
Galveston,  Tex  
Green  Bay,  Wis  
Havre,  Mont  
Kansas  City,  Mo  
Knoxville,  Tenn  
Los  Angeles,  Cal  
Memphis,  Tenn  
New  Orleans,  La  
New  York,  N.  Y  
Norfolk,  Va  
North  Platte,  Neb  
Omaha,  Neb  
Philadelphia,  Pa  
Phoenix  Ariz 

133 
20 
16 
12 
23 
0 
23 
23 
0 
16 
12 

173 
28 
12 
14 
21 
0 
24 
20 
0 
8 
10 

163 
28 
42 
20 
18 
0 
38 
18 
1 
22 
11 

119 
11 
63 
22 
16 
0 
30 
24 
0 
21 
14 

67 
16 
34 
8 

45 
9 
29 
11 

51 
5 
19 
6 

32 
7 
9 
4 

0 
12 
12 
0 

14 
13 

0 
18 
16 
0 
15 
9 

2 
12 
7 
0 
20 
17 

3 

4 
6 
1 
11 
5 

0 
3 
13 
0 
7 
8 

Pittsburg,  Pa  
Rapid  City  S  D 

Roseburg,  Ore  
St  Paul,  Minn 

Salt  Lake  City,  Utah  
San  Francisco,  Cal  

Santa  Fe,  N.  M  
Shreveport,  La  
Spokane,  Wash  

40 
42 
33 
24 
27 
26 
32 

2 
2 
1 
2 
9 
13 
44 

1 

0 
1 

Ib 
4 
1 

21 
2 

1 

0 

1 

3 

0 

1 

1 
2 

3 
1 
0 
4 
16 
33 

Washington,  D.  C  
Wichita,  Kansas  
Williston,  N.  D  

14 
12 
31 

13 
27 
54 

5 
38 
45 

7 
16 
59 

2 
14 
48 

2 
7 
41 

3 
6 
43 

2 
5 
42 

2 
7 
38 

t  774] 


METEOROLOGICAL  DATA 


Sec.  11 


TABLE  118 
TOTAL  NUMBER  OF  THUNDERSTORMS. 

STATIONS 

TJ 

8 
£ 
2 

3 

1 

e 

03 
H» 

o? 
,n 

£ 

1 
15 

'C 
n 
•3 

>> 

0 
<5 

a> 
e 
3 

>-! 

_>. 
g 
NI 

1 

S 

1 

2 

1 

1 

3 

1 
1 

1 

£ 

(5 

Abilene,  Tex  .  .  . 
Albany,  N  Y 

27 
40 
39 
10 
15 
33 
43 
43 
19 
27 
43 
31 
43 
40 
43 
31 
28 
27 
32 
25 
32 
36 
31 
43 
30 
30 
39 
41 
43 
17 
28 
26 
36 
25 
38 
23 
38 
38 
24 
24 
42 
26 
31 

11 

2 
0 
10 
2 
4 
6 
27 
11 
8 
8 
0 
8 
5 
2 
32 
34 
1 
0 
10 
9 
11 
30 
56 
4 
4 
0 
1 
2 
2 
11 
0 
1 
0 
12 

17 
3 
2 
19 
1 
5 
6 
57 
12 
22 
12 
1 
12 
9 
1 
42 
58 
0 
0 
22 
33 
7 
53 
77 
7 
15 
0 
7 
20 
8 
11 
0 
0 
0 
8 

64 
13 
23 
28 
15 
11 
36 
82 
57 
48 
40 
11 
41 
51 
14 
98 
64 
20 
1 
67 
87 
16 
106 
113 
22 
40 
15 
50 
41 
17 
42 
3 
6 
15 
24 

127 
38 
46 
46 
15 
16 
55 
134 
109 
72 
61 
36 
87 
96 
40 
159 
100 
43 
12 
135 
104 
11 
139 
116 
50 
68 
75 
120 
69 
12 
75 
34 
9 
50 
43 

185 
101 
115 
75 
40 
47 
149 
246 
207 
161 
172 
168 
203 
206 
121 
209 
114 
125 
71 
214 
182 

155 
190 
158 
114 
65 
66 
176 
421 
232 
193 
198 
261 
241 
249 
207 
234 
125 
139 
183 
242 
285 

144 
215 
186 
133 
42 
106 
226 
521 
217 
169 
216 
305 
262 
250 
247 
206 
203 
169 
157 
237 
293 

135 
152 
149 
123 
33 
90 
170 
467 
184 
155 
148 
280 
185 
195 
187 
205 
219 
130 
134 
208 
248 

77 
75 
112 
71 
27 
44 
81 
195 
124 
79 
98 
95 
108 
148 
109 
110 
132 
98 
44 
143 
98 

49 
27 
40 
11 
10 
7 
47 
57 
50 
26 
41 
10 
53 
64 
39 
63 
55 
38 
0 
57 
21 

29 
7 
7 
9 
3 
6 
18 
40 
22 
16 
11 
0 
12 
19 
4 
53 
46 
8 
0 
33 
22 
2 
41 
30 
9 
11 
3 
14 
15 
12 
5 
0 
1 
2 
6 

17 
0 
0 
10 
3 
1 
4 
26 
3 
3 
1 
0 
1 
3 
0 
13 
38 
0 
0 
11 
8 
2 
27 
75 
2 
5 
0 
5 
4 
3 
4 
0 
1 
0 
3 

Alpena,  Mich  
Birmingham,  Ala 

Boise,  Idaho  
Boston,  Mass  . 

Buffalo,  N.  Y  

Charleston,  S.  C. 

Chicago,  111  

Cincinnati,  Ohio  

Cleveland,  Ohio  

Denver,  Colo  
Detroit,  Mich 

Dubuque,  Iowa  
Duluth,  Minn 

Fort  Smith,  Ark  
Galveston,  Tex.  .  .  . 

Green  Bay,  Wis 

Havre,  Mont  
Kansas  Citvt  Mo  

Knoxville,  Tenn  

Memphis,  Tenn  
New  Orleans,  La  
New  York,  N.  Y.. 

174 
209 
98 
159 
183 
238 
156 
19 
146 
112 
27 
121 
75 

216 
303 
160 
183 
286 
301 
197 
23 
223 
242 
17 
176 
96 

240 
406 
07 
12 
86 
65 
72 
33 
38 
41 
15 
53 
23 

177 
61 
157 
85 
20 
25 
99 
68 
66 
89 
15 
63 
69 

85 
03 
67 
52 
83 
52 
81 
71 
87 
52 
13 
99 
61 

34 
44 
21 
17 
20 
72 
31 
14 
22 
13 
4 
37 
28 

Norfolk,  Va  

North  Platte,  Neb 

Omaha,  Neb  
Philadelphia,  Pa  
Phoenix,  Ariz  

Pittsburg,  Pa  
Rapid  City,  S.  D 

Roseburg,  Ore  

St  Paul,  Minn  

Salt  Lake  City,  Utah  
San  Francisco,  Cal  
Santa  Fe,  N.  M  
Shreveport,  La  

3 
38 
2 
28 
6 
4 
0 

8 
66 
0 
33 
16 
16 
0 

25 
109 
2 
54 
44 
56 
1 

52 
185 
12 
63 
85 
123 
22 

127 
203 
31 
156 
191 
224 
69 

167 
225 
28 
314 
245 
224 
175 

78 
64 
49 
93 
11 
26 
62 

21 
98 
32 
01 
06 
99 
42 

24 
09 
18 
10 
94 
140 
59 

41 
47 
4 
41 
21 
70 
7 

7 
39 
0 
9 

11 

14 
0 

1 
34 
0 
10 
2 
4 
0 

Spokane,  Wash  
Tampa,  Fla  
Washington,  D.  C  
Wichita,  Kansas  
Williston,  N.  D  

[775] 


Sec.  11 


METEOROLOGICAL  DATA 


TABLE  119 

TOTAL  NUMBER  OF  DAYS  WITH  DENSE  FOG. 

(Fog  of  sufficient  density  to  obscure  buildings  &c.  at  a  distance  of  1000  feet.) 

STATIONS 

1 

£ 
2 
^ 

1 

G 
a 
>-> 

1 
1 
& 

43 
1 

'1 

[ 

1-5 

| 

•^ 

< 

| 

| 

% 
ce 

1 
1 

1 

\ 

1 

Abilene,  Tex  
Albany,  N  Y 

21 
21 
39 
10 
15 
23 
43 
21 
19 
20 
43 
31 
23 
40 
43 
28 
21 
27 
21 
25 
32 
36 
23 
43 
28 
30 
39 
41 
43 
17 
21 
26 
36 
25 
22 
23 
38 
36 
21 
24 
42 
26 
32 

12 
41 
32 
14 
47 
21 
44 
86 
40 
24 
21 
12 
44 
46 
21 
19 
132 
24 
14 
44 
40 
44 
33 
142 
81 
41 
11 
29 
56 
13 
47 
8 
176 
15 
39 
55 
6 
24 
69 
60 
74 
58 
10 

10 
19 
24 
6 
9 
9 
31 
71 
24 
22 
25 

16 
18 
34 
1 
6 
17 
54 
62 
35 
16 
32 

4 
10 
47 
4 
2 
20 
55 
12 
25 
12 
17 

2 
2 
65 
1 
0 
6 
45 
15 
16 
2 
3 

2 
5 
38 
2 
1 
10 
23 
5 
11 
2 
1 

1 
10 
15 
0 
1 
19 
8 
2 
3 
0 
4 

0 
27 
32 
1 
0 
22 

6 
52 
43 
3 
2 
32 
16 
28 
19 
13 
11 

10 
65 
62 
3 
0 
35 
19 
39 
27 
39 
14 
2 
49 
40 
30 
27 
15 
32 
9 
23 
122 
117 
11 
36 
37 
36 
13 
21 
41 
0 
121 

6 
49 
39 
4 
13 
20 
21 
58 
31 
31 
10 
11 
52 
33 
37 
20 
40 
26 
19 
25 
52 
66 
20 
96 
57 
41 
13 
28 
50 
2 
58 
14 
223 
26 
5 
67 
5 
19 
95 
29 
83 
24 
14 

11 
32 
39 
5 
40 
22 
32 
62 
35 
25 
15 
8 
49 
19 
17 
14 
58 
20 
19 
46 
39 
45 
27 
110 
65 
41 
11 
47 
58 
8 
37 
10 
208 
16 
37 
44 
6 
16 
86 
25 
60 
36 
10 

Alpena,  Mich  

Birmingham,  Ala  

Boise,  Idaho  

Boston,  Mass 

Buffalo,  N.  Y  
Charleston,  S.  C  
Chicago,  111.  . 

Cincinnati,  Ohio  
Cleveland,  Ohio  

Detroit,  Mich 

30 

13 
13 
11 
90 
10 
15 
18 
29 
56 
33 
89 
58 
37 
5 
12 
34 
5 
31 

30 
25 
32 
10 
133 
27 
10 
26 
24 
86 
26 
98 
81 
38 
25 
27 
33 
2 
26 

17 
11 
52 
5 
37 
15 
5 
9 
14 
87 

7 
6 
104 
8 
2 
13 
3 
7 
23 
96 

4 
7 
89 
10 
0 
5 
1 
14 
21 
121 

3 
19 
66 
5 
0 
5 
1 
13 
28 
150 

30 
73 
13 
0 
28 
4 
11 
76 
131 

34 
30 
49 
14 
0 
22 
5 
16 
67 
145 

Dubuque,  Iowa  

Duluth,  Minn 

Fort  Smith,  Ark  

Galveston,  Tex  
Green  Bay,  Wis  
Havre,  Mont 

Kansas  City,  Mo  
Knoxville,  Tenn  
Los  Angeles,  Cal  
Memphis,  Tenn  
New  Orleans,  La  
New  York,  N.  Y  
Norfolk,  Va  
North  Platte,  Neb  

39 
47 
9 
6 
9 
12 
0 
22 

14 
60 
20 
9 
10 
5 
0 
13 

12 
26 
6 
16 
8 
6 
0 
18 

16 
14 
4 
19 
9 
7 
0 
19 

9 
8 
4 
16 
12 
14 
0 
38 

7 
33 
10 
39 
15 
32 
0 
73 

Omaha,  Neb  
Philadelphia,  Pa  
Phoenix,  Ariz  

Pittsburg,  Pa  

Rapid  City,  S.  D  
Roseburg,  Ore  

118 
19 
11 
59 
3 
15 
40 
39 
39 
36 
12 

74 
11 
4 
29 
5 
15 
19 
29 
44 
25 

25 
8 
0 
16 

4 
10 

1 

13 
5 
0 
16 
2 
5 
5 

8 
7 
0 
13 
2 
1 
4 

1 
7 
0 
44 
2 
2 
2 

1 
23 
0 
61 
1 
6 
5 

66 
29 
0 
46 
2 
3 
10 

263 
20 
1 
64 
5 
11 
62 

St.  Paul,  Minn  

Salt  Lake  City,  Utah  
San  Francisco,  Cal  
Santa  Fe,  N.  M  
Shreveport,  La  
Spokane,  Wash  
Tampa,  Fla  
Washington,  D.  C  
Wichita,  Kansas  
Williston  N  D 

29 
10 

16 
3 

11 
2 

6 
9 

7 
11 
10 

30 

12 
21 

74 
18 
10 

[  776  J 


METEOROLOGICAL  DATA  Sec.  11 

(3)  Data  on  211  storms  show  a  sleet  formation  less  than  J4" 
for  90  storms  (42.65%) ;   from  %"  to  Y2"  for  62  storms  (29.39%) ; 
from  W  to  1"  for  42  storms  (19.9%);   and  greater  than  I"  for  17 
storms  (8.06%). 

(4)  In  three  instances  the  temperature  fell  below  zero  after  the 
sleet  deposit. 

(5)  The  maximum  recorded  wind  velocity  during  487  sleet  storms 
occurred  simultaneously  with  the  maximum  deposit  of  sleet  in  19 
instances  (3.9%). 

(6)  The  map  (Fig.  429)  is  based  on  the  foregoing  data  and  the 
areas  were  determined  as  follows:   The  total  number  of  damaging 
storms  at  each  station  was  divided  by  the  number  of  years  record. 
The  ratio  thus  obtained  was  located  on  the  map  for  the  station  in 
question.     The  areas  were  then  so  drawn  that  they  included: — 

1st.  Those  stations  at  which  the  ratio  was  approximately  0.2 
or  greater.  This  was  designated  as  the  area  in  which  sleet  storms 
were  frequent. 

2nd.  Those  stations  at  which  the  ratio  was  approximately  0.05 
to  0.2.  This  area  was  designated  as  the  territory  of  occasional 
storms. 

Some  values  greater  than  0.05  lie  outside  of  the  territory  indicated, 
but  as  they  occur  in  isolated  instances,  they  are  not  typical  of  the 
territory,  therefore,  the  numerical  value  of  the  ratio  was  located 
rather  than  indicating  the  territory  with  cross-hatching. 

(7)  The  tabulated  data  given  are  for  towns  and  cities  and  do  not 
represent  the  maximum  conditions  that  may  be  encountered  in 
open  country. 

15.  CORRECTIONS  FOR  BAROMETRIC  PRESSURE 

b=barometric  pressure  at  height  "h"  in  inches. 

b0— barometric  pressure  at  sea  level  in  inches. 

h— -height  above  sea  level  in  feet  at  which  barometric  pressure 
is  desired. 

t=temperature  in  degrees  F  at  altitude  "h." 

Let  H— the  height  in  meters. 

Let  T=the  temperature  in  degrees  C.,  and 

Let  B=the  barometric  pressure  in  millimeters. 
Then,  from  Dr.  William  J.  Humphreys  paper  on  Barometric  Hyp- 
sometry — final  equation. 


H=18,40o(logIO|°)(l+i) 


But  rr  is  a  ratio  and  therefore  B0  and  B  can  be  expressed  in  any 

D 

units,  provided  the  same  unit  is  used  for  both. 

[777] 


Sec.  11 


METEOROLOGICAL  DATA 


TABLE  120 
SLEET  DATA 

LOCATION 
OF 
OBSERVING 
STATIONS 

T3 

1 

r" 

Storm  Reports 

Damaging  Storms 

Most  Severe  Conditions  Reported. 

Number  of 
Sleet  Storms 
reported  for 
Various  Ice 
Formations 

Maximum  Re- 
corded Sleet 
Deposit. 

Max.  Recorded 
Wind  Velocity 
During  Sleet 
Deposit. 

h 
& 

Accompanying 
Recorded  Wine 
Velocity 

a 
S 

£ 
a 

li 

!i 

>$> 

<5 

Ice  Formation 

a 

i 

a 
S 

Thickness  of 
Ice 
Formation. 

K 

H 

•1-1 

1"  + 

Abilene,  Tex  
Albany,  N.Y  
Alpena,  Mich  
Amarillo,  Tex  
Atlanta,  Ga  
Atlantic  City,  N.J.... 
Birmingham,  Ala  
Bismark.N.D  
Boston,  Mass  
Buffalo,  N.Y  
Cairo,  111 

28 
40 
39 
22 
36 

14 
40 
5 
20 
43 
43 
10 
36 
23 
10 
43 
36 
29 
40 
35 
22 
39 
39 
43 
26 
20 
25 
16 
31 
36 
24 
27 
25 
10 
40 
33 
32 
42 
25 
44 
40 
4 
24 
20 
36 

2 
29 
4 
1 
3 

3E 
5 
4 
28 
6 
4 
16 
1 
14 

io8 

2 

5 
4 
10 
1 
2 
9 
4 

4g 
.3* 

g 

It' 

2 
29 

g 
g 

88 
3 
17 

14 
g 

3E 
61 

g 

2a 
29a 
4a 
1 
3a 

0 

0 
5 
4d 
28 
6f 
1 
2 
Id 
3 
0 
10 
2h 
li 
2 
6a 
0 
2d 
9a 
3 

0 

4d 
o 
13 

0 

o 

11 

0 
0 
0 
0 
0 
1 
3 
17a 
7 
0 
0 
3 
0 
0 

.5" 
.5" 
1" 
.25" 

.5»g 

2.8e 
2"e 
.3" 
1" 

1"+ 

.5" 
.6" 

.29" 

t"e 
1.62e 

.5 

.3" 
.5" 

4.3e 
2.8e 

18NW 
36 
29E 
13N 

25E 

28W 

29NE 
28 
31NE 
20NE 

14 

44 
12 

40 
20 
31N 
26 

42 

40W 
18 

16NE 
26NE 
23 
36W 

20 
36 

12° 

23° 

17° 

31.4° 

14° 
30° 
0° 

16° 

24° 
10° 
14° 

22° 

23 
36 
48SW 
13N 
30ED 

56N 
45NE 
72SW 
28 
34NE 
30W 
14 
48NE 

47 
32N 
23 
27 
26 
40 
31 
31 
32 

48 
20E 

40W 
32 
40 

48N 
26NE 
52N 

36W 

20 
36 

.25" 

.5" 

.25" 

.5" 

.03" 

2"e 
.2" 
.5" 

1"+ 

.5" 
.29" 

.75" 

1" 

4.3e 
2.8e 

12° 

29° 

3° 
27° 

8° 

1° 

14° 

28° 

22° 

6° 

24° 
11° 

14° 

22° 

l 

27b 

1 
1 

4 
2c 

7 

c 

Ic 
c 

c 
c 

1 

c 
c 
c 

c 
c 

c 
c 
5 

c 
c 

1 

c 
32 

2 
c 

c 

1 
1 

8 

3c 
3c 
4 

3 

1 

Ic 
8 

4 

2 

3 

5 

2 
1 

c 

6 
2 

1 
1 

3 

2 

1 

1 

c 

Charleston,  S.  C  
Charlotte,  N.  C  
Chattanooga,  Tenn  
Chicago,  111  

Cincinnati,  Ohio  
Cleveland,  Ohio  
Columbus,  Ohio  
Concordia,  Kansas.... 
Denver,  Colo 

Des  Moines,  la  
Detroit,  Mich 

Dodge  City,  Kansas... 
Dubuque,  la  
Duluth,  Minn  
Eastport,  Maine  
Erie,  Pa  
El  Paso,  Tex  
Evansville,  Ind  
Fort  Smith,  Ark  
Galveston,  Tex  
Grand  Haven,  Mich.  .  . 
Green  Bay,  Wis  
Harrisburg,  Pa  
Hartford,  Conn  
Hatteras,  N.C  
Havre,  Mont 

Huron,  S.  D  
Indianapolis,  Ind  
Kansas  City,  Mo  
Keokuk,  Iowa 

Knoxville,  Tenn  
Lansing,  Mich  
Little  Rock,  Ark  
Louisville,  Ky  
Los  Angeles,  Cal  

[778] 


METEOROLOGICAL  DATA 


Sec.  11 


TABLE  120—  Continued 

LOCATION 
OF 
OBSERVING 
STATIONS 

Years  record 

Storm  Reports 

Damaging  Storms 

Most  Severe  Conditions  Reported. 

Number  of 
Sleet  Storms 
reported  for 
Various  Ice 
Formations. 

Maximum  Re- 
corded Sleet 
Deposit. 

Max  Recorded 
Wind  Velocity 
During  Sleet 
Deposit. 

Ice  Formation 

Accompanying 
Recorded  Wind 
Velocity 

P. 
1 

.a 

It 

Ice  Formation 

a 

H 
a 

Thickness  of 
Ice 
Formation 

H 

I- 

h 

1"  + 

Lynchburg,  Va  
Marquette,  Mich  
Memphis,  Tenn  
Milwaukee,  Wis  
Nantucket,  Mass  
Nashville,  Tenn  
New  Orleans,  La  
Norfolk,  Va  
North  Platte,  Neb... 
Oklahoma,  Okla  
Omaha,  Neb  
Parkersburg.W.Va.. 
Philadelphia,  Pa  
Phoenix,  Ariz  

42 
27 
40 
41 
27 
39 
40 
43 
39 
15 
41 
25 
18 
17 
23 
39 
42 

27 
26 
40 
36 
42 
38 
37 
40 
14 
16 
25 
33 
35 
25 
22 
12 
24 
23 
26 
26 
35 
20 

1 
6 

7 
12 
4 

7 

g 

8 
4 
3 
5 
1 

4 
6 
18 

/ 

1 
g 
£ 
5 
g 
2 
1 
13 

9 

g 
3 
g 
4 
8 
3 

t" 

la 
6 
7 
12 

3 
5 
0 
0 

4 
0 

1 

k 
3 
0 
3 

.38" 

.9"e 
1.5f 
1" 
1.75 
•5 

.5" 
1" 

1" 

1"! 

1.5e 
.2 
!.38 

L0.4e 
2.5e 

15 
33 
16 
37 
83NE 
37 

14 
28 
28 
10NE 
30 

20N 
19 
40 

29 

17 

55 

JO 
30 

18NE 

36 

15 
28NW 

18 

31° 
10° 

27° 
28° 
29° 

30° 

2° 

8° 
8° 

15 
33 
38 
40 
83NE 
37 

54NW 
38N 
30 
17 
34NE 

36NW 
26NE 
40 

6 

9 
8 
55 

0 
8 

2S 

WNE 
4 
ON 

0 

.38" 
.9e 

1.75" 
.5" 

.75" 
.75" 

.5 
.2 

.38 
.25" 

.4 

31° 
10° 

27° 
10° 
29° 

2° 
8° 

c 
1 
c 
c 
2 

c 
c 
c 
c 
c 

c 
c 
2c 

c 

c 

c 

c 

2c 

c 

c 
c 
c 

1 

3 

1 

1 

2 
2 

5 

c 
2 

c 

4 
1 
2 
1 

3 
1 

1 

2 
2 
3 

1 
2 

Pierre,  S.  D  
Pittsburg.Pa  
Portland,  Me  
Pueblo,  Colo  
Raleigh,  N.C  
Rapid  City,  S.  D  
Rochester,  N.  Y  
Roseburg,  Oregon.... 
San  Francisco,  Cal  .  .  . 
Salt  Lake  City,  Utah. 
Sandusky,  Ohio  
Santa  Fe.N.M  

Scranton,  Pa  
Shreveport,  La  
Sioux  City,  la  

Spokane,  Wash  
Springfield,  111  
Springfield,  Mo  
St.  Paul,  Minn  
Syracuse,  N.  Y  
Tampa,  Fla  
Toledo,  Ohio  
Washington,  D.  C...  . 
Wichita,  Kansas  
Williston,  N.  D  
Wilmington,  N.C.  .  .  . 

(a)  Damage  to  telephone  and  telegraph  wires  and  poles,     (b)  Probable  thickness  ranging 
from  Ty  to  Y±'  of  ice.    (c)  D?ta  incomplete  as  regards  thickness  of  ice.    (d)  Damage  to 
telephone,  telegraph  and  electric  wires,    (e)  -This  thickness  was  the  ice  and  snow  deposit  on 
the  ground  and  not  on  wires  for  which  there  is  no  data,      (f  )  Damage  to  telephone  and  telegraph 
wires,    (g)  Report  practically  no  sleet  damage,    (h)  200  telegraph  poles  down  30  miles 
southeast  of  city  in  one  of  these  storms,    (i)  One  (1)  inch  of  ice  formed  on  telephone  wires 
and  100  poles  broken  at  Miltonvale,  20  miles  southeast  of  station,     (j)  Estimated,     (k)  No 
records.    (1)  Not  government  records  (obtained  by  consulting  officials  of  Telephone  and  Tele- 
graph Companies. 

[779] 


Sec.  11 


METEOROLOGICAL  DATA 


JL I  *j 

~""r3         ~~!  i 


780  ] 


METEOROLOGICAL  DATA 


Sec.  11 


Therefore, 


and, 


TT 


Iog10b=log10b0  — 

18,400(^1+^ 

But  h=3.28  H,  and  numerically,  Tm=5/9  (t, 
Hence, 


32). 


3.28 


18,400 


Iog10b=log10b0— 

Iog10b=log10bo  — 

Problem  No.  1. 

Find  the  equivalent  sea  level  barometric  pressure  at  an  altitude 
of  6000  feet  when  the  temperature  is  60°  F.  assuming  the  reading  of 
the  barometer  is  24.5". 


56,422+122.8  t 


TABLE  121 

WIND  VELOCITIES,  AS  INDICATED  BY  A  ROBINSON 
ANEMOMETER,  CORRECTED  TO 
TRUE  VELOCITIES. 

Indicated 
Velocity. 

^0 

+1 

+2 

^3 

+« 

-M 

+6 

+7 

+8 

+9 

0 

5.1 

6.0 

6.9 

7.8 

8.7 

10 

9.6 

10.4 

11.3 

12.1 

12.9 

13.8 

14.6 

15.4 

16.2 

17.0 

20 

17.8 

18.6 

19.4 

20.2 

21.0 

21.8 

22.6 

23.4 

24.2 

24.9 

30 

25.7 

26.5 

27.3 

28.0 

28.8 

29.6 

30.3 

31.1 

31.8 

32.6 

40 

33.3 

34.1 

34.8 

35.6 

36.3 

37.1 

37.8 

38.5 

39.3 

40.0 

50 

40.8 

41.5 

42.2 

43.0 

43.7 

44.4 

45.1 

45.9 

46.6 

47.3 

60 

48.0 

48.7 

49.4 

50.2 

50.9 

51.6 

52.3 

53.0 

53.8 

54.5 

70 

55.2 

55.9 

56.6 

57.3 

58.0 

58.7 

59.4 

60.1 

60.8 

61.5 

80 

62.2 

62.9 

63.6 

64.3 

65.0 

65.7 

66.4 

67.1 

67.8 

68.5 

90 

69.2 

[  781  ] 


Sec.  11         GALVANIZING  AND  SHERARDIZING 

Solution: 

From  Table  122  for  6000  feet  and  60°  F.  find  the  correction  factor 
per  100  feet  elevation  =  0.084. 

fiOOO 
The  total  correction  is~~-X  0.084=5.04". 

Sea  level  barometric  pressure  =  24.5""+  5.04"  =  29.54". 

Problem  No.  2. 

Find  the  barometric  pressure  at  an  altitude  of  6500  feet  when 
the  temperature  is  50°  F.  assuming  the  sea  level  barometric  pressure 
is  29.92". 

Solution  : 

From  Table  122  for  6500  .feet  and  50°  F.  find  the  correction  factor 
per  100  feet  elevation  =  0.085. 

AC  nn 

The  total  correction  w-rgp  X  0.085  =  5.525". 
The  barometric  pressure  is  29.92—5.525=24.395". 

Problem  No.  3. 

Find  the  barometric  pressure  at  an  altitude  of  10,000  feet  when 
the  temperature  is  50°  F.  assuming  a'  sea  level  pressure  of  29.92". 

Solution  : 

Iog10b=loglob0 


loglo  29.92  =  1.47596 

i         u         i  AVXM  10,000 

Iog10b  =  1.47596  -  ^;422 

loglob  =  1.31612. 

b  =  20.707" 

16.  HOT  GALVANIZING.  This  process  consists  in  covering 
wrought  iron,  cast  iron,  or  steel  with  a  coating  of  melted  zinc.  To 
insure  perfect  contact  bejbween  the  zinc  and  the  metal  it  is  neces- 
sary to  remove  all  paint,  grease,  etc.,  by  the  use  of  benzine  or  a  simi- 
lar solvent. 

In  preparing  cast  iron  the  metal  is  further  cleansed  by  hydro- 
fluoric acid  to  remove  the  sand.  In  preparing  wrought  iron,  a 
pickling  solution  of  sulphuric  acid  is  used,  and  the  surface  then 
scratch-brushed  to  remove  scale.  It  may  sometimes  be  necessary 
to  remove  certain  oils  with  caustic  potash.  The  cleansed  material 
is  dipped  in  muriatic  acid  and  after  having  been  thoroughly  dried 
is  dipped  in  melted  zinc  at  a  temperature  of  about  800°  F.  When 
thoroughly  coated  the  articles  are  withdrawn  through  clean  metal, 
where  the  flux  has  been  skimmed  back,  and  then  drained  and  cooled 
in  a  tank  of  running  water.  The  finished  surface  should  be  clean, 
smooth  and  free  from  blisters  and  dross. 

[782] 


GALVANIZING  AND  SHERARDIZING 


Sec.  11 


CM 


S  8 

3    2 


sssiiilllliiili 


11*11 


*§  8*   3   3 


[  783  ] 


g    s 

£    3 

<!      00 


B    If 


Sec.  11         GALVANIZING  AND  SHERARDIZING 

17.  SHERARDIZING.  Sherardizing  is  the  process  whereby  a 
film  of  zinc  dust  is  deposited  on  iron  or  steel.  To  insure  perfect 
contac*  between  the  zinc  and  the  article  to  be  sherardized,  it  is 
necessary  to  pickle  iron  or  steel  in  sulphuric  acid  and  cast  or  malleable 
iron  in  hydrofluoric  acid  to  remove  the  sand.  After  pickling  the 
articles  are  boiled  in  hot  water  to  remove  the  acid  and  then  dried. 
When  thoroughly  dry,  the  material  to  be  sherardized  is  placed  in  a 
drum  containing  loose  zinc  dust.  The  drum  is  not  completely  filled 
and  on  being  rotated  allows  the  material  to  shift  about  in  the  drum 
thus  bringing  all  the  metallic  surfaces  in  contact  with  the  zinc 
dust.  The  drums  are  heated  to  a  temperature  of  about  750°  F. 
during  the  six  or  eight  hours  that  this  process  continues.  The 
zinc  coats  the  surface  and  alloys  with  the  iron  for  a  small  distance 
below  the  surface.  After  sherardizing  the  article  should  have  a 
smooth  gray  color. 

18.  SPECIFICATION  FOR  GALVANIZING  IRON 
OR  STEEL.* 

These  specifications  give  in  detail  the  test  to  be  applied  to  gal- 
vanized material.  All  specimens  shall  be  capable  of  withstanding 
these  tests. 

a — Coating.  The  galvanizing  shall  consist  of  a  continuous  coating 
of  pure  zinc  of  uniform  thickness,  and  so  applied  that  it  adheres 
firmly  to  the  surface  of  the  iron  or  steel.  The  finished  product  shall 
be  smooth. 

b — Cleaning.  The  samples  shall  be  cleaned  before  testing,  first 
with  carbona,  benzine  or  turpentine,  and  cotton  waste  (not  with  a 
brush),  and  then  thoroughly  rinsed  in  clean  water  and  wiped  dry 
with  clean  cotton  waste. 

The  samples  shall  be  clean  and  dry  before  each  immersion  in  the 
solution. 

c — Solution.  The  standard  solution  of  copper  sulphate  shall  con- 
sist of  commercial  copper  sulphate  crystals  dissolved  in  cold  water, 
about  in  the  proportion  of  36  parts,  by  weight,  of  crystals  to  100 
parts,  by  weight,  of  water.  The  solution  shall  be  neutralized  by 
the  addition  of  an  excess  of  chemically  pure  cupric  oxide  (Cu  O). 
The  presence  of  an  excess  of  cupric  oxide  will  be  shown  by  the  sedi- 
ment of  this  reagent  at  the  bottom  of  the  containing  vessel. 

The  neutralized  solution  shall  be  filtered  before  using  by  pass- 
ing through  filter  paper.  The  filtered  solution  shall  have  a  specific 
gravity  of  1.186  at  65  degrees  Fahrenheit  (reading  the  scale  at  the 
level  of  the  solution)  at  the  beginning  of  each  test.  In  case  the  fil- 
tered solution  is  high  in  specific  gravity,  clean  water  shall  be  added 
to  reduce  the  specific  gravity  to  1.186  at  65°  F.  In  case  the  filtered 
solution  is  low  in  specific  gravity,  filtered  solution  of  a  higher  specific 

*  Standard  National  Electric  Light  Association  Specification. 

[  784] 


GALVANIZING  AND  SHERARDIZING         Sec.  11 

gravity  shall  be  added  to  make  the  specific  gravity  1.186  at  65 
degrees  Fahrenheit. 

As  soon  as  the  stronger  solution  is  taken  from  the  vessel  containing 
the  unfiltered  neutralized  stock  solution,  additional  crystals  and 
water  must  be  added  to  the  stock  solution.  An  excess  of  cupric 
oxide  shall  always  be  kept  in  the  unfiltered  stock  solution. 

d— Quantity  of  Solution.  Wire  samples  shall  be  tested  in  a 
glass  jar  of  at  least  two  (2)  inches  inside  diameter.  The  jar  without 
the  wire  samples  shall  be  filled  with  standard  solution  to  a  depth 
of  at  least  four  (4)  inches.  Hardware  samples  shall  be  tested  in  a 
glass  or  earthenware  jar  containing  at  least  one-half  (}/%)  pint  of 
standard  solution  /or  each  hardware  sample. 

Solution  shall  not  be  used,  for  more  than  one  series  of  four  im- 
mersions. 

e — Samples.  Not  more  than  seven  wires  shall  be  simultaneously 
immersed,  and  not  more  than  one  sample  of  galvanized  material, 
other  than  wire,  shall  be  immersed  in  the  specified  quantity  of  solu- 
tion. 

The  samples  shall  not  be  grouped  or  twisted  together,  but  shall 
be  well  separated  so  as  to  permit  the  action  of  the  solution  to  be 
uniform  upon  all  immersed  portions  of  the  samples. 

f — Test.  Clean  and  dry  samples  shall  be  immersed  in  the  required 
quantity  of  standard  solution  in  accordance  with  the  following  cycle 
of  immersions. 

The  temperature  of  the  solution  shall  be  maintained  between  62 
and  68  degrees  Fahrenheit  at  all  times  during  the  following  test. 

First — Immerse  for  one  minute,  wash  and  wipe  dry. 

Second — Immerse  for  one  minute,  wash  and  wipe  dry. 

Third — Immerse  for  one  minute,  wash  and  wipe  dry. 

Fourth — Immerse  for  one  minute,  wash  and  wipe  dry. 

After  each  immersion  the  samples  shall  be  immediately  washed 
in  clean  water  haying  a  temperature  between  62  and  68  degrees 
Fahrenheit,  and  wiped  dry  with  cotton  waste. 

In  the  case  of  No.  14  galvanized  iron  or  steel  wire,  the  time  of 
the  fourth  immersion  shall  be  reduced  to  one-half  minute. 

g — Rejection.  If  after  the  test  described  in  Section  "f"  there 
should  be  a  bright  metallic  copper  deposit  upon  the  samples,  the 
lot  represented  by  the  samples  shall  be  rejected. 

Copper  deposits  on  zinc  or  within  one  inch  of  the  cut  end  shall 
not  be  considered  causes  for  rejection. 

In  the  case  of  a  failure  of  only  one  wire  in  a  group  of  seven  wires 
immersed  together,  or  if  there  is  a  reasonable  doubt  as  to  the  copper 
deposit,  two  check  tests  shall  be  made  on  these  seven  wires,  and  the 
lot  reported  in  according  with  the  majority  of  the  set  of  tests. 

Note: — The  equipment  necessary  for  the  tests  herein  outlined  is 
as  follows: 

Filter  paper. 

Commercial  copper  sulphate  crystals. 

[785] 


Sec.  11  CONCRETE 

Chemically  pure  cupric  oxide  (Cu  O). 

Running  water. 

Warm  Water  or  ice  as  per  needs. 

Carbona,  benzine  or  turpentine. 

Glass  jars  at  least  2  inches  inside  diameter  by  at  least  4J^  inches 
high. 

Glass  or  earthenware  jars  for  hardware  samples. 

Vessel  for  washing  samples. 

Tray  for  holding  jars  of  stock  solution. 

Jars,  bottles  and  porcelain  basket  for  stock  solution. 

Cotton  waste. 

Hydrometer  cylinder,  3  inches  diameter  by  15  inches  high. 

Thermometer  with  large  Fahrenheit  scale  correct  at  62  and  68 
degrees. 

Hydrometer  correct  at  1.186  at  65  degrees  Fahrenheit. 

19.  CONCRETE.* 

Cement: — The  production  of  Portland  Cement  in  this  country 
is  now  so  standardized  that  any  brand  of  Portland  Cement  will 
pass  the  standard  tests  provided  the  cement  in  question  is  a  repre- 
sentative sample  of  the  maker's  output.  The  chief  usefulness  of  the 
specifications  is  therefore  to  secure  the  proper  quality  rather  than  to 
discriminate  between  brands.  It  should  not  be  understood  that  all 
cement  is  necessarily  satisfactory,  since  any  particular  lot  may  have 
been  injured  by  an  error  in  manufacture;  or  improper  or  overlong 
storage.  Any  reputable  manufacturer  can  and  does  make  a  satis- 
factory cement,  and  the  cement  tests  should  therefore  be  used  to 
guard  against  error.  The  manipulation  of  the  tests  and  the  require- 
ments to  be  met  by  the  cement  have  been  very  completely  standard- 
ized, in  what  are  known  as  the  Standard  Specifications  for  Cement, 
copies  of  which  may  be  obtained  from  any  cement  manufacturer, 
or  from  the  Association  of  Portland  Cement  Manufacturers,  Phila- 
delphia, Pa. 

Proportions: — The  proportions  of  cement,  sand  and  stone,  or 
gravel  will  depend  somewhat  upon  the  purpose  for  which  the  con- 
crete is  to  be  used.  In  general,  the  smaller  the  volume  and  the 
greater  the  stresses,  the  richer  the  concrete  should  be.  Further, 
if  the  concrete  is  to  be  impervious  to  water  or  to  be  immersed  in 
water  or  deposited  through  water,  the  mixture  should  be  richer,  i.e. 
with  a  larger  amount  of  cement,  than  would  otherwise  be  necessary. 
Concrete  is  more  impervious,  permanent  and  stronger  when  it  is 
of  the  maximum  density,  and  the  maximum  density  obtainable 
from  any  given  sand,  cement  and  stone,  or  gravel,  will  be  that  due 
to  one  certain  proportion  of  the  ingredients.  The  proper  proportions 
in  any  particular  case  will  be  determinate  by  tests  designed  to 
disclose  the  voids  in  the  aggregates  which  should  be  completely 

*From  Pole  and  Tower  Lines  by  R.  D.  Coombs. 

[786] 


CONCRETE  Sec.  11 

filled  by  the  sand  and  the  cement.  Ordinarily  however,  it  is  not 
necessary  to  make  such  tests,  as  the  customary  proportions  com- 
bined with  good  workmanship  ivill  produce  a  satisfactory  result. 
The  amounts  of  sand  and  stone  have  usually  been  given  separately, 
although  in  reality  there  should  be  two  proportions,  that  of  the 
cement  and  that  of  the  combined  sand  and  stone.  The  most 
commonly  used  proportions  are:  1  :  6  (1  :  2  :  4)  for  fine  work,  and 
(1  :  9)  (1  :  3  :  6)  for  mass  foundations,  etc. 

Aggregates: — The  aggregates,  which  are  the  sand,  gravel,  broken 
stone,  slag,  cinders,  chats,  etc.  may  be  of  various  sizes  from  screenings 
to  fairly  large  stones.  They  should  however,  be  of  graded  sizes 
in  order  to  present  fewer  voids.  Inasmuch  as  concrete  is  in  reality 
an  artificial  stone,  its  constituent  parts  must  be  free  from  vegetable 
matter  and  soft  particles,  or  the  resulting  product  will  be  in  the 
nature  of  "rotten  rock."  It  is  frequently  specified  that  the  sand 
and  other  aggregates  shall  be  clean,  although  a  small  percentage  of 
clay  is  generally  permissible,  since  neither  sand  nor  gravel  will  be 
perfectly  clean  without  very  thorough  washing.  It  has  also  been 
required  that  the  broken  stone  shall  be  sharp,  but  this  is  generally 
not  necessary  since  a  high  grade  of  concrete  may  be  made  with 
gravel,  and  gravel  is  never  sharp  Sharp  sand,  however,  is  desirable. 

Water: — The  water  used  in  mixing  concrete  should  be  free  from 
oils,  acids,  or  any  very  considerable  amount  of  alkali  or  vegetable 
matter.  Satisfactory  water  is  very  generally  obtained  throughout 
the  country,  and  usually  near  the  site  of  the  work.  Although, 
"dry'1  concrete  has  been  used  to  a  considerable  extent  abroad,  and 
was  formerly  used  somewhat  in  this  country, — the  present  practice 
is  to  use  "wet  concrete."  By  wet  concrete  is  meant  concrete  mixed 
with  sufficient  water  to  be  semi-fluid,  so  that  it  may  readily  flow 
around  the  reinforcing  or  encased  material,  and  be  easily  tamped 
or  puddled  so  as  to  completely  fill  out  the  forms,  and  obtain  an 
efficient  adherence  to  the  reinforcing,  etc.  The  only  objection  to 
the  use  of  an  excess  of  water  is  that  some  of  the  cement  will  be 
washed  away  or  deposited  separately,  and  that  the  resulting  con- 
crete sets  and  drys  more  slowly,  delaying  the  work.  Since  the 
water  is  needed  both  for  fluidity,  and  for  chemical  combination,  a 
sufficient  quantity  must  be  provided  to  prevent  its  absorption  by, 
or  drying  on,  the  aggregates.  In  warm  weather  particularly,  it  is 
desirable  to  thoroughly  wet  down  the  pile  of  stone  from  which  the 
material  is  taken. 

Mixing  and  Placing: — Concrete  may  be  mixed  either  by  hand 
or  by  mechanical  mixers,  the  method  in  any  instance  depend- 
ing upon  the  quantity  to  be  made,  and  the  availability  of  a 
mixer  at  the  site.  Machine  mixing  is  probably  more  thoroughly 
done  than  hand  mixing,  although  just  as  good  concrete  can  be  made 
by  hand  under  proper  supervision.  In  hand  mixing,  the  materials 
should  be  mixed  upon  a  flat  form  or  floor,  in  order  to  prevent  an 
undue  loss  of  cement  bearing  water,  or  the  admixture  of  earth,  etc. 

[  787  ] 


Sec.  11  CONCRETE 

Mixing  floors  are  of  various  sizes  from  about  6  feet  square  up  to 
much  larger  areas,  but  in  any  case  it  is  desirable  that  tongue  and 
grooved  lumber,  or  two  layers  of  lumber,  be  used  in  order  to  prevent 
excessive  leakage  through  the  cracks.  In  order  to  obtain  the  proper 
proportions,  some  unit  of  measurement  such  as  a  bucket  or  a  wheel- 
barrow should  be  used  to  transport  the  aggregates  from  the  stock 
pile  to  the  mixing  platform.  It  is  then  a  simple  matter  for  the 
workman  to  regularly  take  so  many  units  of  sand,  another  number 
of  units  of  stone,  and  the  specified  number  of  bags  of  cement  to 
make  each  batch  of  concrete.  The  sand  and  stone  are  first  placed 
upon  the  mixing  board  and  mixed  by  turning  the  pile  over  with 
shovels;  the  cement  is  then  spread  over  the  mass  which  is  turned, 
water  being  added  during  the  turning.  The  number  of  turns  to  bo 
given  each  process,  and  the  faithfulness  with  which  the  work  is  done 
determines  the  excellence  of  the  mixing.  Mixing  should  be  continued 
until  the  mass  presents  a  uniform  appearance,  and  the  stone  appears 
to  be  all  covered  with  sand  and  cement.  As  soon  as  the  mixing  is 
completed,  the  material  should  be  taken  in  water  tight  buckets  or 
barrows,  and  placed  in  the  work.  The  size  of  the  batch  should 
depend  upon  the  amount  that  can  be  immediately  used,  ^  since 
material  left  on  the  board  for  any  considerable  time  takes  an  initial 
set,  and  is  useless  for  future  work. 

The  placing  of  the  concrete  material  should  be  as  nearly  continuous 
as  practicable  in  order  to  prevent  clevage  planes  or  planes  of  little 
coherence  at  the  points  where  one  day's  work  joins  another.  Such 
surfaces  will  contain  a  layer  of  "dead"  material  as  well  as  a  certain 
amount  of  dirt  which  floats  on  the  surface,  and  in  poor  grades  of 
work  the  joint  can  be  distinctly  seen  on  the  sides  of  the  structure. 
Since  it  is  not  always  possible  to  work  continuously,  the  temporary 
surface  should  be  left  rough  and  must  be  thoroughly  washed  and 
preferably  scrubbed  before  continuing  operations.  Reinforced 
concrete  poles  should  always  be  made  in  one  operation  as  they  are 
entirely  too  small  to  justify  the  risks  attendant  on  non-continuous 
work. 


[788] 


SECTION  11 

PART  II 

RULES  FOR 

RESUSCITATION 

FROM 

ELECTRIC  SHOCK 

Recommended  by 

Commission  on  Resuscitation  from 
Electric  Shock 

Representing 

The  American  Medical  Association 

The  National  Electric  Light  Association 

The  American  Institute  of  Electrical  Engineers 


Issued  by 
NATIONAL  ELECTRIC  LIGHT  ASSOCIATION 

Engineering  Societies  Building 
New  York 


RESUSCITATION  FROM  ELECTRIC  SHOCK 

SUPERINTENDENTS,  FOREMEN  AND  OTHERS  HAVING 
CHARGE  OF  MEN,  ARE  ADVISED  TO  GIVE  PRACTICAL  IN- 
STRUCTIONS AND  DEMONSTRATIONS  ON  THE  USE  OF 
THESE  RULES  TO  ALL  OLD  AND  NEW  EMPLOYEES. 

PHYSICIANS  WHO  MAY  BE  CALLED  UPON  IN  CASES  OF 
SHOCK  SHOULD  BE  GIVEN  COPIES  OF  THESE  INSTRUC- 
TIONS, AND  WHERE  PRACTICABLE,  PLACED  IN  COM- 
MUNICATION WITH  THE  PHYSICIAN  OF  THE  ELECTRICAL 
COMPANY. 

The  prone-pressure  method  of  artificial  respiration  described 
in  these  rules  (Section  HI)  is  equally  applicable,  after  clearing  the 
mouth  and  throat  of  froth,  to  resuscitation  of  the  apparently  drowned, 
and  also  to  cases  of  suspended  respiration  due  to  inhalation  of  gas 
or  to  other  causes. 


COMMISSION  ON  RESUSCITATION  FROM  ELECTRIC 
SHOCK 

DR.  W.  B.  CANNON,   Chairman 

Professor  of  Physiology,  Harvard    University 
DR.  GEORGE  W.  CHILE 

Professor  of  Surgery,   Western  Reserve    University 
DR.  YANDELL  HENDERSON 

Professor  of  Physiology,    Yale    University 
DR.  S.  J.  MELTZER 

Head  of  Department  of  Physiology  and  Pharmacology,   Rockefeller  Institute 

for  Medical  Research 
DR.  EDW.  ANTHONY  SPITZKA 

Director  and  Professor  of  General  Anatomy,  Daniel  Bauyh  Institute  of  Ana- 
tomy, Jefferson  Medical  College 
MR.  W.  C.  L.  EGLIN 

Past-President,  National  Electric  Light  Association 
DR.  A.  E.  KENNELLY 

Professor  of  Electrical  Engineering,  Harvard  University 
DR.  ELIHU  THOMSON 

Electrician,  General  Electric  Company 
MR.  W.  D.  WEAVER,  Secretary 

Editor,  Electrical  World 


[790] 


TREATMENT  FOR  ELECTRIC  SHOCK 

An  accidental  electric  shock  usually  does  not  kill  at  once,  but 
may  only  stun  the  victim  and  for  a  while  stop  his  breathing. 

The  shock  is  not  likely  to  be  immediately  fatal,  because: 

(a)  The  conductors  may  make  only  a  brief  and  imperfect  contact 
with  the  body. 

(6)  The  skin,  unless  it  is  wet,  offers  high  resistance  to  the  current. 

Hope  of  restoring  the  victim  lies  in  prompt  and  continued  use 
of  artificial  respiration.  The  reasons  for  this  statement  are: 

(a)  The  body  continuously  depends  on  an  exchange  of  air,  as 
shown  by  the  fact  that  we  must  breathe  in  and  out  about  fifteen 
times  a  minute. 

(6)  If  the  body  is  not  thus  repeatedly  supplied  with  air,  suffocation 
occurs. 

(c)  Persons  whose  breathing  has  been  stopped  by  electric  shock 
have  been  reported  restored  after  artificial  respiration  has  been 
continued  for  approximately  two  hours. 

The  Schafer,  or  "prone  pressure"  method  of  artificial  respiration, 
slightly  modified,  is  illustrated  and  described  in  the  following  re- 
suscitation rules.  The  advantages  of  this  method  are: 

(a)  Easy  performance;  little  muscular  exertion  is  required. 

(6)  Larger  ventilation  of  the  lungs  than  by  the  supine  method. 

(c)  Simplicity;    the  operator  makes  no  complex  motions  and 
readily  learns  the  method  on  first  trial. 

(d)  No  trouble  from  the  tongue  falling  back  into  the  air  passage. 

(e)  No  risk  of  injury  to  the  liver  or  ribs  if  the  method  is  executed 
with  proper  care. 

Aid  can  be  rendered  best  by  one  who  has  studied  the  rules  and 
has  learned  them  by  practice  on  a  volunteer  subject. 


INSTRUCTIONS  FOR  RESUSCITATION 
Follow  these  Instructions  Even  if  Victim  Appears  Dead. 

L— BREAK  THE  CIRCUIT  IMMEDIATELY 

1.  With  a  single  quick  motion  separate  the  victim  from  the  live 
conductor.  In  so  doing  avoid  receiving  a  shock  yourself.  Many 
have,  by  their  carelessness,  received  injury  in  trying  to  disconnect 
victims  of  shock  from  live  conductors. 

Observe  the  Following  Precautions 

(a)  Use  a  dry  coat,  a  dry  rope,  a  dry  stick  or  board,  or  any  other 
dry  non-conductor  to  move  either  the  victim  or  the  wire,  so  as  to 
break  the  electrical  contact.  Beware  of  using  metal  or  any  moist 
material.  The  victim's  loose  clothing,  if  dry,  may  be  used  to  pull 

[  791  ] 


Sec.  11 


RESUSCITATION 


[  792  ] 


RESUSCITATION 


Sec.  11 


[793] 


Sec.  11  RESUSCITATION 

him  away;  do  not  touch  the  soles  or  heels  of  his  shoes  while  he 
remains  in  contact — the  nails  are  dangerous. 

(6)  If  the  body  must  be  touched  by  your  hands,  be  sure  to  cover 
them  with  rubber  gloves,  mackintosh,  rubber  sheeting  or  dry 
cloth;  or  stand  on  a  dry  board  or  on  some  other  dry  insulating  sur- 
face. If  possible,  use  only  one  hand. 

If  the  victim  is  conducting  the  current  to  ground,  and  is  con- 
vulsively clutching  the  live  conductor,  it  may  be  easier  to  shut 
off  the  current  by  lifting  him  than  by  leaving  him  on  the  ground 
and  trying  to  break  his  grasp. 

2.  Open  the  nearest  switch,  if  that  is  the  quickest  way  to  break  the 
circuit. 

3.  If  necessary  to  cut  a  live  wire,  use  an  ax  or  a  hatchet  with  a 
dry  wooden  handle,  or  properly  insulated  pliers. 

II.— SEND  FOR  THE  NEAREST  DOCTOR 

This  should  be  done  without  a  moment's  delay,  as  soon  as  the 
accident  occurs,  and  while  the  victim  is  being  removed  from  the 
conductor. 

HI.— ATTEND  INSTANTLY  TO  VICTIM'S  BREATHING 

(1)  As  soon  as  the  victim  is  clear  of  the  live  conductor,  quickly 
feel  with  your  finger  in  his  mouth  and  throat  and  remove  any  foreign 
body  (tobacco,  false  teeth,  etc.).     Then  begin  artificial  respiration 
at  once.    Do  not  stop  to  loosen  the  patient's  clothing;  every  moment 
of  delay  is  serious. 

(2)  Lay  the  subject  on  his  belly,  with  arms  extended  as  straight 
forward  as  possible,  and  with  face  to  one  side,  so  that  the  nose  and 
mouth  are  free  for  breaching  (see  Figure  430).     Let  an  assistant 
draw  forward  the  subject's  tongue. 

If  possible,  avoid  so  laying  the  subject  that  any  burned  places 
are  pressed  upon. 

Do  not  permit  bystanders  to  crowd  about  and  shut  off  fresh  air. 

(3)  Kneel  straddling  the  subject's  thighs  and  facing  his  head; 
put  the  palms  of  your  hands  on  the  loins  (on  the  muscles  of  the  bmall 
of  the  back),  with  thumbs  nearly  touching  each  other,  and  with 
fingers  spread  over  the  lowest  ribs  (see  Figure  430.) 

(4)  With  arms  held  straight,  swing  forward  slowly  so  that  the 
weight  of  your  body  is  gradually  brought  to  bear  upon  the  subject 
(see  Figure  431).     This  operation,  which  should  take  from  two  to 
three  seconds,  must  not  be  violent — internal  organs  may  be  injured. 
The  lower  part  of  the  chest  and  also  the  abdomen  are  thus  com- 
pressed, and  air  is  forced  out  of  the  lungs. 

(5)  Now  immediately  swing  backward  so  as  to  remove  the  pressure, 
but  leave  your  hands  in  place,  thus  returning  the  position  shown  in 
Figure  430.     Through  their  elasticity,  the  chest  walls  expand  and 
the  lungs  are  thus  supplied  with  fresh  air. 

(6)  After  two  seconds  swing  forward  again.     Thus  repeat  de- 

[794] 


RESUSCITATION  Sec.  11 

liberately  twelve  to  fifteen  times  a  minute  the  double  movement  of 
compression  and  release — a  complete  respiration  in  four  or  five 
seconds.  If  a  watch  or  a  clock  is  not  visible,  follow  the  natural 
rate  of  your  own  deep  breathing — swinging  forward  with  each 
expiration,  and  backward  with  each  inspiration. 

While  this  is  being  done,  an  assistant  should  loosen  any  tight 
clothing  about  the  subject's  neck,  chest  ,or  waist. 

(7)  Continue  artificial   respiration    (if  necessary,   two  hours  or 
longer),  without  interruption,  until  natural  breathing  is  restored,  or 
bags  filled  with  warm  (not  hot)  water.     The  attention  to  keeping 
until  a  physician  arrives.     Even  after  natural  breathing  begins, 
carefully  watch  that  it  continues.     If  it  stops,  start  artificial  respira- 
tion again. 

During  the  period  of  operation,  keep  the  subject  warm  by  applying 
a  proper  covering  and  by  laying  beside  his  body  bottles  or  rubber 
the  subject  warm  should  be  given  by  an  assistant  or  assistants. 

(8)  Do  not  give  any  liquids  whatever  by  mouth  until  the  subject 
is  fully  conscious. 

First  Care  of  Burns 

When  natural  respiration  has  been  restored,  burns,  if  serious, 
should  be  attended  to  until  a  doctor  comes. 

A  raw  or  blistered  surface  should  be  protected  from  the  air.  If 
clothing  sticks,  do  not  peel  it  off — cut  around  it.  The  adherent 
cloth,  or  a  dressing  of  cotton  or  other  soft  material  applied  to  the 
burned  surface,  should  be  saturated  with  picric  acid  (0.5  per  cent.). 
If  this  is  not  at  hand,  use  a  solution  of  baking  soda  (one  teaspoonful 
to  a  pint  of  water),  or  the  wound  may  be  coated  with  a  paste  of 
flour  and  water.  Or  it  may  be  protected  with  a  heavy  oil,  such  as 
machine  oil,  transformer  oil,  vaseline,  linseed,  carron  or  olive  oil. 
Cover  the  dressing  with  cotton,  gauze,  lint,  clean  waste,  clean 
handkerchiefs,  or  other  soft  cloth,  held  lightly  in  place  by  a  bandage. 

The  same  coverings  should  be  lightly  bandaged  over  a  dry, 
charred  burn,  but  without  wetting  the  burned  region  or  applying 
oil  to  it. 

Do  not  open  blisters. 


[  795  ] 


INDEX 


PAGE 

Abrasion  Molding 713 

Absolute  Temperature,  Definition .        3 
A.  C.  Lightning  Arrester  Grounds.  433 
Single-Phase,  Three- Wire  Sys- 
tem, Calculation 477 

Single-Phase  System,  Calcula- 
tion    474 

Single-Phase,  Vector  Diagram  454 
Series  System,  Calculation ...  482 
Series  System,  Description.  .  .   450 
Systems,  Method  of  Calcula- 
tion   469 

Three-Phase,  Three- Wire  Sys- 
tem, Description 445 

Three-Phase  System,  Calcula- 
tion   478 

Three-Phase,  Four-Wire  Sys- 
tem, Description 448 

Three-Phase    System,    Vector 

Diagram 457 

Three  -  Phase,     Transformer 

Connections 448 

Two-Phase,    Three-Wire   Sys- 
tem, Calculation 477 

Two-Phase,    Three-Wire  Sys- 
tem, Vector  Diagram 456 

Two-Phase,     Four-Wire    Sys- 
tem, Description 445 

Additions  to  Existing  System,  Cal- 
culation    481 

Additions,  Vector 454 

Admittance,  Definition 3 

Aerial  Cable,  Definition 3 

Conductor,  Definition 3 

Line  Construction,   Specifica- 
tions  674-749 

Ageing  of  Transformer  Core,  Defi- 
nition         3 

Ageing  of  Transformer  Steel..  .321-337 

Insulators 298 

Agents,  Preservative 585 

Air-Break  Switches 413 

Air-Core  Trans^rmer,  Definition.       3 

Air-Gap,  Definition 3 

Air-Path,  Definition 3 

Air-Reluctance,  Definition 3 

Allerdyce  Process  of  Wood  Preser- 
vation    601 

Alphabet,  Greek 57 

Alternate    Hot    and    Cold    Treat- 
ment, Wood  Preservation 605 

Alternating  Current,  Definition.  .3,  441 
Five- Wire  System,  Two-Phase, 
Description 445 


PAGE 

Alternating  Current,  Single-Phase, 
Three-Wire  System,  Descrip- 
tion     443 

Single-Phase     System,     Two- 
Wire,  Description  of 443 

Two-Phase,  Four- Wire  System  455 
Two-Phase,    Three-Wire   Sys- 
tem, Description 443 

Alternation,  Definition 3 

Periodicity  of,  Definition 4 

Alternating  Current  Power,  Defini- 
tion        4 

Aluminum,  Definition 4 

Cables,    Weatherproof    Insu- 
lated, Specification  for 257 

Cell  Lightning  Arresters 403 

Location  of  Ores 179 

Reduction  of 178 

Refining  of 179 

Aluminum  Wire,   Bare,   Specifica- 
tion for 257 

Copper  Equivalent,  Table  of. .  247 

Loading  Table 541 

Special  Sizes,  Table  of 247 

Table  of  Physical  Constants. .    185 
Weatherproof  Insulated,  Spec- 
ification     257 

American  Wire  Gauge,  Definition 

of 4 

Amount  of  Oil  Necessary  for  Creo- 

soted  Pine  Poles 635 

Ampere,  Definition 5 

Hour,  Definition 5 

Second,  Definition 5 

Turn,  Definition 5 

Turns,  Secondary,  Definition.     47 
Amplitude  of  Vibration  of  Wave, 

Definition 5 

Analysis    Specification,    Coal-Tar 

Creosote 624 

for  Mixed  Oils,  Wood  Preser- 
vation    629 

Water-Gas-Tar  Creosote 629 

Anchor  Guys 704 

Guy,  Locating  Foot  of 706 

Log,  Definition 5 

Anchors,  Patented  Guy 284 

Angle  of  Lag  or  Lead  of  Current, 

Definition  of 5 

Angle,  Phase,  Definition 43 

Angular  Velocity,  Definition  of ...       5 

Annual  Service  Charge 660 

Apparent  Efficiency,  Definition ...       5 
or  Equivalent  Resistance, Defi- 
nition of 6 


[797  ] 


INDEX 


403 
409 
409 
36 
745 
407 


406 
398 
404 
687 

6 

278 
278 

6 


PAGE 

Apparent  Power,  Definition 5 

Application  of  Rubber  Compound .    182 
Arbor  Vitse  Logging Ill,  112 

Time  of  Cutting 1 

Where  Grown 1 

Arc  Lamp  Cut-outs 414 

Areas  of  Circles,  Tables  of 95-99 

Armor  of  Cable,  Definition  of  ....        6 
Arresters,   Aluminum   Cell  Light- 
ning    403 

Compression  Lightning 397 

Electrolytic  Lightning.  .  . 

Grounding  of  Lightning . . 

Horn 

Lightning,  Definition.  .  .  . 

Lightning  Installation  of. 

Lightning,  Location  of - 

Multi-gap  Lightning 397 

Multipath  Lightning 

Pole  Line 

Single  Gap  Lightning 

Artificial  Foundation  For  Poles. 

Asbestos,  Definition  of 

Attaching  Insulators  to  Pins .  .  . 

Pins  to  Cross-arms 

Axis  of  Co-ordinates,  Definition. 
Auto  Transf9rmers,  Definition  ..6,319 
Automatic  Circuit-Breaker,  Defini- 
tion         6 

Switch,  Definition 6 

Auxiliary  Specification,  Wood  Pres- 
ervation     630 

B 

Back  Yard,  Rights-of-Way 683 

Balanced  Circuit,  Definition 6 

Balanced  Load  of  System,  Defini- 
tion   6 

Bare,  Hard-Drawn  Copper  Wire, 

Specification 252 

Barometric  Corrections,  Table  of .  .  783 

Pressure,  Corrections  for 777 

Barrow- Reel,  Definition 7 

Beg-Ohms,  Definition. 7 

Bends  in  Line,  Calculation  of  Pole 

Strength 557 

Bending  Moment  Formulae,  Table 

of 526 

Formulae 523 

Bethel  Process  of  Wood  Preserva- 
tion   597 

Bicro,  Definition 7 

Bight  of  Cable,  Definition 7 

Bimetallic  Wire,  Definition 7 

Blowing  a  Fuse,  Definition 7 

Blowing  Point  of  Fuse,  Definition  7 

Bolts,  Carriage 279 

Cross-arm 279 

Specification  for  Carriage  .  279-281 
Specification  for  Cross-arm. 279-281 
Booster  Transformer,   Calculation 

of  Capacity 504 

Braces,  Attaching  to  Pole 690 

Cross-arm 278 


PAGE 

Braces,  Specifications  for  Cross-arm  279 

Bracing  of  Buck-arms 695 

of  Cross-arms 690 

Flexible  Towers,  Function  of.  161 

of  Steel  Poles,  Function  of .  .  .  155 

of  Steel  Towers,  Function  of.  155 

Brackets,  Poles 284 

Bracket,  Saddle,  Definition 47 

Braided  Wire,  Defini^n 7 

Branch  Circuits,  Definition 7 

Cut-out,  Definition 7 

Lines 720 

Breaker,  Circuit,  Definition 10 

Breaking  Down  of  Insulation,  Defi- 
nition    7 

Strength  of  Wires,  Solid,  Table 

of 215 

Strength  of  Wires,  Stranded, 

Table  of 216 

Britannia  Joint,  Definition 7 

Bronze,  Definition 7 

Browne  &  Sharpe  Gauge,  Law  of. .  196 
Brush  Combined  with  Open  Tank 
Treatment,  Wood  Preserva- 
tion   610 

and  Spray  Discharge,  Defini- 
tion   7 

Treatment,    Wood    Preserva- 
tion   650 

Buck-Arms 693 

bracing  of 695 

Buck-Arm  Gains 681 

Bunched  Cable,  Definition  of 7 

Burnett  Process  of  Wood  Preserva- 
tion   600 

Butt  Rot...               123 


Cable,  Aerial,  Definition 3 

Aluminum,  Weatherproof  In- 
sulated, Specification 257 

Armor  of,  Definition 6 

Bight  of,  Definition 7 

Capacity  of,  Definition 9 

Casing,  Definition 8 

Concentric,  Definition 11 

Copper,    Weatherproof    Insu- 
lated, Specification 251 

Core,  Definition 8 

Definition 8 

Duplex,  Definition 8,  18 

Grip,  Definition 8 

House,  Definition 8 

Lead  Encased 36 

Paper,  Definition . 41 

Submarine,  Definition 8 

Vault,  Definition 8 

Calculation  of  A.  C.  Systems 469 

of  Additions  to  Existing  Sys- 
tems  -  ..   481 

Characteristics,        Suspension 

Insulators 308 

of  D.  C.  Series  System 469 

of  D.  C.  Two- Wire  System. . .  464 


[798] 


INDEX 


PAGE 
Calculation  of  Dead  End  Loading 

of  Poles 556 

of  Edison  Three-Wire  System.  469 

of  Guying 557 

of    Pole    Strength,    Bends   in 

Line 557 

of  Pole  Stresses 549 

of  Regulators,  Capacity 503 

of  Regulation,  Voltage  Regu- 

lators 501 

of  Stresses  on  Cross-arms .  .  .      547 
of   Single   Phase,    Three-Wire 

System 477 

of     Single-Phase,      Two- Wire 

System 474 

of  Strength  of  Rotted  Poles .  .   553 

of  Three-Phase  System 478 

of  Transformer  Capacity 494 

of  Transformer  Efficiency 500  . 

of  Transformer  Regulation.  .  .   498 
of     Two-Phase,      Three-Wire 

System .  .    477 

of  Two-Wire   D.   C.   Railway 

System 466 

Capacity  of  Cable,  Definition 9 

Carrying,  Definition 9 

Condenser,  Definition 12 

Dielectric,  Definition 17 

Distributed,  Definition 17 

Electrostatic,  Definition 9,20 

Electrostatic,  Unit  of,  Defini- 
tion         9 

Formulae  for 463 

of  Line,  Definition 9 

Reactance,  Definition 9 

Solid  Wire,  Table  of 226 

Stranded  Wire,  Table  of 228 

Suspension  Insulators 304 

of       Suspension       Insulators, 

Grading  of 311 

of  Transformer,  Calculation  of  494 

Cap  Wire,  Definition 8 

Carbon,  Definition 9 

Card  Process  of  Wood  Preserva- 
tion    600 

Carriage  Bolts 279 

Bolts,  Specification  for.  .  .  .279-281 
Carrying  Capacity,  Definition  ....        9 

Cartridge  Fuses 422 

Cases,  Transformer 324 

Casing,  Cable,  Definition  of 8 

Cat  Faces 124 

Catenary  Curve,  Definition 9 

Cedar,  Western  Red,  Absorption  of 

Creosote 662 

Western    Red,    Tank    Treat- 
ment with  Creosote 661 

Cell,  Electrolytic,  Definition 20 

Cement,  Insulator 295 

Insulator,  Property  of 295 

Cementing  Together,  Built-up  In- 
sulators     294 

Center  of  Distribution,  Definition. 9,  17 

of  Distribution,  Locating  of.  .   490 

Centigramme,  Definition 9 


PkGE 

Centimeter,  Definition 9 

Centimeter-Gramme-Second     Sys- 
tem, Definition 9 

Characteristic  Curve,  Definition . .       9 

Characteristics,  Transformer 345 

Charging  Current,  Effect  on  Line 

Calculation 460 

Solid  Wire,  Table  of 238 

Stranded  Wire,  Table  of 244 

Charge,  Electric,  Definition 10 

Charges    on    Transmission    Lines, 

Electric  Causes 393 

Chestnut  Poles,  Dimensions  of ....   126 

Logging  of 112-114 

Poles,  Specification  for 125 

Time  of  Cutting 113 

Where  Grown 112 

Choke  Coils 411 

Coil,  Definition 10,  319 

Choice  of  Preservatives,  Wood  Pres- 
ervation     619 

of    Voltage    on    Transmission 

Line 484 

Circuit,  Balanced,  Definition 6 

Branch,  Definition 7 

Breaker,    Automatic,    Defini- 
tion         6 

Breaker,  Definition 10 

Constant-Potential,        Defini- 
tion       \& 

Earth,  Definition 18 

Electric,  Definition 10 

Ground,  Definition 24 

High  Tension,  Definition 32 

Inductive,  Definition 33 

Leg  of,  Definition 36 

Multiple,  Definition 10,  39 

Multiple-Series,  Definition ...     39 

Open,  Definition 10, 41 

Parallel,  Definition 10 

Polyphase,  Definition 44 

Series,  Definition 10 

Series- Multiple,  Definition.  .  .     48 

Short,  Definition 48 

Circular  Mil,  Definition 10 

Circumferences  of  Circles,  Tables 

of 95-99 

Clays  for  Porcelain  Insulators 289 

Clearing  Obstacles,  by  Pole  Line. .   685 

Clockwise  Motion,  Definition 10 

Coal-Tar  Creosote 587 

Creosote,    Analysis   Specifica- 
tion    624 

Creosote,  Production  of 587 

Creosote,  Specification 621 

Coefficient  of   Expansion,   Defini- 
tion        10 

Hysteresis,  Definition 11,  32 

of  Mutual  Inductance,  Defini- 
tion       11 

of  Self-Inductance,  Definition     11 

Temperature 193,  194 

Temperature,  Definition 51 

Temperature,  Table  of 192-194 

Coils,  Choke 411 


[799] 


INDEX 


PAGE 

Coils,  Choke,  Definition 10,  319 

Flat  Formed 323 

Impedance,  Definition 32 

Inductance,  Definition 33 

Primary  of  Transformer,  Defi- 
nition       44 

Reactance,  Definition 319 

Tertiary 382 

Transformer 321 

Cold  Preservative,  Steeping  in 602 

Waves 760 

Colorie,  Definition 8 

Coloring  of  Glaze,  Porcelain,  In- 
sulators    291 

Come  Along,  Definition 

Combination  Pins 274 

Common    Logarithms,     of    Num- 
bers  59-83 

Return,  Definition 11 

Comparative  Weight  of  Conduc- 
tors, Electrical  System 450 

Comparison  of  Oil  Preservatives .  .   595 

of  Resistance  Units 189 

of  Strength,  Steel  Poles  and 

Steel  Towers 159 

of    Y   and  "A"  Transformer 

Connections 450 

of  Wire  Gauges 195 

of  Wood  Preservative 664 

Compensator,  Definition 11,  319 

Complete  Wave,  Definition 11 

Components  of  Impedance,  Defini- 
tion      11 

Composite  Wire,  Definition 11 

Composition  Insulators 296 

Compound,  Application  of  Rubber  182 

Definition 11 

Compressed  Gas  Expulsion  Fuse .  .   428 
Compression  Lightning  Arresters  .  397 

and  Tension  Formulae 523 

Concentric  Cable,  Definition 11 

Winding 323 

Concrete,  Description  of 786 

Pole,  Flexibility  of 141 

Poles,  Forms  for 136 

Poles,  Handling  of 141 

Poles,  Hollow 141 

Poles,     Hollow,     Method    of 

Manufacture 141,142 

Poles,  Mixture  of  Concrete. . .    139 

Poles,  Molding  of 140 

Poles,  Reinforced 135 

Poles,  Solid 135,136 

Poles,  Steel  Reinforcing 136 

Poles,  Strength  of  Concrete. .  .    139 

Strength  of 139 

Condenser,  Definition 12 

Capacity,  Definitiuo 12 

Conductance,  Definition 12 

Conductivity,  Electric,  Definition .      12 

Matthiessen's  Standard 190 

Relative 190 

Relative,  Table  of 191 

Specific 190 

Specific,  Definition 49 


PAGE 

Conductors 177 

Aerial,  Definition 3 

Definition 12 

Negative,  Definition 39 

Neutral,  Definition 39 

Overhead,  Definition 41 

Sag  of,  Definition 47 

Stranded,  Definition 50 

Connecting  Single-Phase  Load  to 

Polyphase  Systems 498 

Sleeve,  Definition 12 

Connection,  Multiple,  Definition. .      12 

Series,  Definition 12 

Testing  of  Ground 433 

Constant,  Definition 12 

Current,  Definition 12 

Current  Transformers,  Defini- 
tion of 12,  319 

Potential  Circuit,  Definition...     12 

Voltage  Transmission 511 

Construction,  Transformer 319 

Consumer's  Services 745 

Continuous  Current,  Definition  13,  439 
Convection  Currents,  Definition.  .  13 
Convective  Discharge,  Definition.  13 

Conversion  Tables 102-104 

Co-ordinates,  Axis  of,  Definition .  .        6 

Co-periodic,  Definition 13 

Co-Phase,  Definition 13 

Copper,  Definition 13 

Cables,  Weatherproof  Insulat 

ed,  Specifications  for 251 

Clad  Billets,  Production  of .  .      180 
Clad,  Steel  Wire,  Hard-Drawn 

Specification 254 

Clad   Wire,    Internal   Induct- 
ance of 247 

Clad  Wire,  Table  of  Physical 

Constants 186 

Location  of  Ore 177 

Loss,  Definition 13 

Loss  Tests,   Induction  Regu- 
lators    386 

Losses,  Transformers 330 

Loss  Test,  Transformers 359 

Reduction  of 177 

Refining  of 177 

Wire, Current  Carrying  Capac- 
ity, Table  of 204 

Wire,     Hard-Drawn,     Defini- 
tion      26 

Wire,  Hard-Drawn,  Specifica- 
tion    252 

Wire,  Loading  Table 538 

Wire,  Soft  Drawn,  Definition .      49 
Wire,  Stranded,    Bare    Load- 
ing Table 538 

Wire,        Specifications        for 

Weather-proof  Insulated. .     251 
Wire,  Table  of  Physical  Con 

stants 184 

Core,  Cable,  Definition 8 

Lamination  of,  Definition ...        13 

Laminated,  Definition 36 

Losses,  Definition 13 


[  800  ] 


INDEX 


PAGE 
Core  Loss  Test,  Transformers  ....   355 

Transformer 320 

Type  Transformers 320 

Corner  Poles,  Wiring  of 720 

Corona  and  Corona  Loss 484 

Definition 13 

Corrections  for  Barometer,  Table 

of 783 

for  Barometric  Pressure 777 

for  Wind  Velocities,  Table  of . .  781 

Cosine,  Definition 13 

Co-Tangent,  Definition 14 

Coulomb,  Definition 14 

Counter-Electromotive-Force.Defi- 

nition 14 

of  Induction,  Definition 14 

Couple,  Definition 14 

Creosote,  Coal-Tar 587 

Coal-Tar,  Analysis  Specifica 

tion 624 

Coal-Tar,  Specification 621 

Oil  for  Brush  Treatment,  Spec- 
ification    633 

Water-Gas-Tar 592 

Water-Gas-Tar,    Specification 

of 629 

Wood 594 

Creosoted  Pine  Cross-arms,  Speci- 

cation  of 270 

Creosoted    Pine    Poles,    Specifica- 
tion for 634 

Yellow    Pine    Poles,    Dimen- 
sions of 134 

Yellow  Pine  Poles,  Specifica- 
tion for 134 

Creosoting  Pine  Cross-arms,  Speci- 
fication     638 

Pine    Poles,    Amount    of    Oil 

Necessary 635 

Pine  Poles,  Specification 635 

Crib  Bracing  for  Poles 686 

Cross-arms 267 

Bolts 279 

Bolts,  Specification  for.       279-281 

Braces 278 

Bracing 690 

Braces,  Specifications  for 279 

Buck 693 

Calculation  of  Stresses 547 

Creosoted  Pine  Specifications 

for 637 

Definition 14 

Double 692 

Equipping  with  Insulators .  .  .   695 

Fitting  to  Poles 690 

Gains 681 

Guys 709 

Location  of 691 

Method  of  Attaching  Pins.  . .   278 

Painting  and  Treating 690 

Pins 695 

Preservative  Treatment  of ...   561 

Seasoning 565 

Size 690 

Size  to  Use 690 


PAGE 

Cross-arms,  Special 270 

Specification  for 267 

Specifications  for  Creosoting 

Pine 638 

Storing 566 

Steel 270 

Treating  Plants,  Open  Tank, 

Description  of 644 

Cross,  Electric,  Definition 14 

Crossings,  Street 683 

Cross-section  Area,  B.  &  S.  Gauge, 

Table  of 196 

Cruciform  Type  Transformers. ...   321 

Curb  Line,  Location  of  Poles 685 

Current,  Alternating,  Definition.. 3, 441 
Alternating,     Series    System, 

Description 450 

Carrying    Capacity,    Copper 

Wire,  Table  of 204 

Constant,  Definition 12 

Continuous,  Definition 13 

Convection,  Definition 13 

Density  of.  Definition 16 

Determination  from  Wattage, 

Definition 14 

Distribution,  Definition 14 

Earth,  Definition 18 

Electric,  Definition 14 

Energy  Component  of,  Defi- 
nition      21 

Fusing,  Definition 23 

Foucault,  Definition 15 

Harmonic,  Definition 26 

Heating  Effects  of 200 

High  Potential,  Definition...  .     32 

Induced,  Definition : 

Lagging,  Definition 36 

Leading,  Definition 36 

Mean,  Definition 38 

Normal,  Definition 40 

Oscillatory,  Definition 41 

Polyphase,  Definition 15,  44 

Primary,  Definition 45 

Pulsating,  Definition 45 

Rush,  Definition 15 

Secondary,  Definition 47 

Simple  Periodic,  Definition. . .      15 

Stray,  Definition 50 

Strength  of,  Definition 15,  50 

Table  of  Fusing  Effects 199 

Table  of  Heating  Effects 202 

Curve,  Catenary,  Definition 9 

Characteristic,  Definition ....       9 
Characteristic,  Transformer .  .   345 

Sinusoidal,  Definition 49 

Cut-out,  Arc  Lamp 414 

Definition , 16 

Block,  Definition 16 

Branch,  Definition 7 

Single-pole,  Definition 49 

Switch,  Definition 16 

Cycle,  Definition  of 16,  441 

Hysteretic,  Definition 32 


[801  J 


INDEX 


PAGE 

Dead  End  Loading  of  Poles,  Calcu- 
lations of 556 

Man,  Definition 16 

Deeay  of  Wood 583 

Decimal  Equivalents,  Table  of 94 

Defects,  Wood  Poles 123 

Definition  Regulators 319 

Transformers 319 

of  Transmission  and  Distribu- 
tion Systems 439 

Deflection  Formulae,  Table  of 526 

Delta-Connection,  Definition 16 

Delta  Three-Phase  System,  Defini- 
tion       16 

Demand,  Definition 16 

Factor,  Definition 16 

Density,  Definition 16 

of  Current,  Definition 16 

of  Field.  Definition 16 

Surface,  Definition 50 

Description  of  Open  Tank  Plants .    641 

of  Vectors 452 

Design-Transformers 333 

Determination    of    Current    from 

Wattage,  Definition 14 

Devices,  Grounding 432 

Diagrams,  Vector 451 

Vector,  Definition 53 

Diameter  of  Wire,  Brown  &  Sharpe 

Gauge 196 

of  Wire,  Solid,  Table  of 217 

of  Wires,  Stranded,  Table  of. .   218 

Dielectric,  Definition 16 

Capacity,  Definition 17 

Disruptive  Strength  of,  Defini- 
tion       17 

Hysteresis,  Definition 17 

Resistance,  Definition 17 

Strain,  Definition 17 

Strength,   Transformer    Insu- 
lation     346 

Difference,  Phase,  Definition 43 

Dimensions  of  Chestnut  Poles 126 

of     Creosoted     Yellow     Pine 

Poles 134 

of  Eastern  White  Cedar  Poles  127 

of  Idaho  Cedar  Poles 130 

of  Red  Cedar  Poles 130 

of  Sawed  Red  Wood  Poles ...    132 

of  Western  Cedar  Poles 130 

of  Western  White  Cedar  Poles  130 

of  Yellow  Pine  Poles 133 

Dipping,  Definition 17 

Direct  Current,  Definition  of 439 

Railway,  System,  Description  439 
Railway  System,   Method  of 

Calculating 466 

Series  Lighting  System,  Des- 
cription    440 

Series  System,  Method  of  Cal- 
culating    469 

Series  System,  Thury,  Descrip- 
tion    440 


PAGE 

Direct  Current,   Three-Wire  Sys- 
tem, Description 440 

Three-Wire  System,    Method 

of  Calculating 469 

Two-Wire  System,  Method  of 

Calculating 464 

Two-Wire    System,    Descrip- 
tion    439 

Discharge,  Definition 17 

Convective,  Definition 13 

Disruptive,  Definition 17 

Electrostatic,  Definition .....     20 

Static,  Definition 50 

Surging,  Definition 50 

Disruptive  Discharge,  Definition. .      17 
Strength  of  Dielectric,  Defini- 
tion       17 

Dissipation  of  Energy,  Definition..     17 
Distributed  Capacity,  Definition. .      17 

Inductance,  Definition 17 

Distributing  Mains,  Definition. ...      18 

Systems,  Description  of 439 

Distribution,  Center  of,  Definition  9,  17 

Current,  Definition 14 

Locating  the  Center  of 490 

Series,  Definition 48 

Systems  of 722 

Diversity  Factor,  Definition 18 

Draw  Vise,  Definition 18 

Drawing  Wire 181 

Drop,  Definition 18 

Ohmic,  Definition 40 

of  Potential,  Definition 18 

Reactive,  Definition 45 

of  Voltage,  Definition 18 

Dry  Process,  Porcelain  Insulators.   291 

Duplex  Cable,  Definition 18 

Duplex  Wire,  Definition .  . 18 

Dynamic  Electricity,  Definition. . .      18 
Dyne,  Definition 18 

£ 

Earth  Circuit,  Definition 18 

Currents,  Definition 18 

Easement,  Definition 18 

Eastern  White  Cedar  Poles,   Di- 
mensions of 127 

Specification  for.  . 127 

Economics  of  Transmission 506 

Eddy  Currents,  Definition 19 

Losses-Transformers 329 

Edison   Three-Wire   System,    De- 
scription    440 

Method  of  Calculating 469 

Effect  of  Charging  Current  on  Line 

Calculation 460 

of  different  types  of  pins  on 

Insulator  characteristics 297 

of  Ground,  Definition 24 

Effects  of  Higher  Harmonics,  De- 
finition    29 

Effect,  Page,  Definition 41 

Skin,  Definition 49 


[  802  ] 


INDEX 


PAGE 

Effective  Capacity  Suspension  In- 
sulators   304 

Electromotive-Force,     Defini- 
tion   19 

Mechanical    Stress    on    Insu- 
lators   296 

Reactance,  Definition 19 

Resistance 205 

Resistance,  Definition 19 

Efficiency,  Apparent,  Definition  of  5 

Efficiency,  Definition 19 

Transformers 335 

Transformer,  Calculation  of. .  500 

Elastic  Limit,  Definition 19 

Elasticity,  Modulus  of,  Definition.  39 

Electric  Charge,  Definition 10 

Charges       on       Transmission 

Lines,  Causes 393 

Circuit,  Definition 10 

Conductivity,  Definition 12 

Cross,  Definition 14 

Current,  Definition 14 

Energy,  Definition 21 

Gradient,  Definition 23 

Horse-Power,  Definition 32 

Insulator,  Definition 34 

Potential,  Definition 44 

Quantity,  Definition 45 

Shock,  Resuscitation  from  .  .  .  789 

Surgings,  Definition 50 

Transmission,  Definition 52 

Wave,  Definition 55 

Electrical    Characteristics    of    In- 
sulators   297 

Systems,  Comparative  Weight 

of  Conductor 450 

Tests  on  Insulators 299-301 

Electricity,  Dynamic,  Definition .  .  18 

Static,  Definition 50 

Electrification,  Definition 19 

Electro-chemistry,  Definition 19 

Electrolysis,  Definition 20 

Electrolyte,  Definition 20 

Electrolytic  Cell,  Definition 20 

Lightning  Arresters 403 

Electro-Magnetic  Units,  Definition  19 

Electro-Metallurgy,  Definition 19 

Electro-Motive    Force,    Effective, 

Definition 19 

Energy  Component  of,  Defini- 
tion   21 

Impressed,  Definition 33 

Electro-Motive    Forces,    Induced, 

Definition 33 

Mean,  Definition 38 

Electro-Motive    Force,     Primary, 

Definition 45 

Reactive,  Definition 46 

Wattless  Component  of,  Defi- 
nition    55 

Electro-Negative,  Definition 19 

Ions,  Definition 20 

Electro-plating,  Definition 20 

Electro-positive,  Definitions 20 

Ions,  Definition 20 


PAGE 
Electrostatic  Capacity,  Definition .  8,  20 

Unit  of,  Definition  of 9 

Electrostatic  Discharge,  Definition  20 

Field,  Definition 20 

Force,  Definition 20 

Induction,  Definition 20 

Lines  of  Force,  Definition 20 

Potential,  Definition 20 

Units,  Definition 20 

Enclosed  Fuses 422 

Energy,  Definition 20 

Component  of  Current,  Defi- 
nition    21 

Component  of  Electro-Motive 

Force,  Definition 21 

Dissipation  of,  Definition 17 

Electric,  Definition 21 

Potential,  Definition 44 

Equalizer  Feeder,  Definition 21 

Equations,  Transformer 327 

Equipotential,  Definition 21 

Equivalents,  Decimal,  Table  of ...  94 
Equivalent  Resistance,  Definition 

of 6 

Resistance,  Definition 21 

Resistance  and  Reactance  of 

Transformers 332 

Erg,  Definition 21 

Exciting  Current,  Transformers . . .  330 

Test  Transformers 355 

Existing  Systems,  Calculations  for 

Additions  to 481 

Expansion,  Coefficient  of,  Defini- 
tion   10 

Expulsion  Type  Fuse. .  .* 426 

Extra  Galvanized   Steel   Strands, 

Table  of 213 

F 

Factor,  Demand,  Definition 16 

Diversity,  Definition 18 

Reactance,  Definition 45 

Reactive,  Definition 46 

Fahrenheit    Thermometric    Scale, 

Definition 21 

Failure  of  Insulators 298 

Structural  Steel  Poles 151 

Structural  Steel  Towers 151 

Farad,  Definition 21 

Fatigue  of  Iron  or  Steel,  Magnetic, 

Definition 21 

Magnetic,  Definition 37 

Feed,  Definition 21 

Feeder,  Definition. .  21 

Distribution,  Definition. .....  21 

Equalizer,  Definition 21 

Feeders,  Negative,  Definition 39 

.Neutral,  Definition 39 

Feeding  Point,  Definition 22 

Field,  Density  of,  Definition 16 

Electrostatic,  Definition ....  20 

Magnetic,  Definition 37 

Resultant    Magnetic,    Defini- 
tion   47 


t  803  ] 


INDEX 


PAGE 

Field,  Stray,  Definition 50 

Fire    Killed    Poles,    Western    Red 
Cedar 117 

Firing  and  Glazing  Porcelain  In- 
sulators    291 

Five-Wire,     Two-Phase     System, 
Description 445 

Flat  Formed  Coils 323 

Flexible  Towers 160 

Function  of  Bracing 161 

Flexibility  of  Concrete  Poles 141 

Flux,  Magnetic,  Definition 37 

Paths,  Magnetic,  Definition  .  .      37 

Foot-Pound,  Definition 22 

Per-Second,  Definition 22 

Force,  Electrostatic,  Definition ...     20 

Lines  of ,  Definition 36 

Magnetic,  Definitions 37 

Magnetizing,  Definition 38 

Forms  for  Concrete  Poles 136 

Formula  for  Bending  Moment. . .  .   523 

for  Capacity 463 

for  Compression  and  Tension .   523 

for  Inductance 463 

for  Line  Supports  at  Different 

Levels 529 

for  Resultant  Load  on  Wire .  .   527 

for  Shearing 523 

for  Torsion 524 

for  Weight  of  Wire  and  Ice... .    527 

for  Wind  Pressure 523 

for  Wind  Pressure  on  Wires .  .   527 

Foucault  Current,  Definition 15 

or  Eddy  Currents,  Definition .     22 

Four- Wire,    Three-Phase   System, 

Description 448 

Two-Phase  System,   Descrip- 
tion    445 

Frequency,  Definition 441 

Fundamental,  Definition 23 

High,  Definition 31 

Fundamental    Frequency,    Defini- 
tion      23 

Units t 102-104 

Function     of     Bracing,     Flexible 

Towers 161 

of  Bracing  Steel  Poles 155 

of  Bracing  Steel  Towers 155 

Periodic,  Definition 41 

Fuse 417 

Block,  Definition 23 

Blocks,  Installation 736 

Blowing  a,  Definition 7 

Blowing  Point  of,  Definition . .        7 

Box,  Definition 23 

Compressed  Gas  Expulsion. .  .   428 

Cartridge 422 

Electric,  Definition 23 

Enclosed 422 

Expulsion  Type 426 

Link 420 

Links,  Definition 23 

Oil-Immersed 425 

Safety,  Definition 47 


PAGE 

Fusing  Current,  Definition 23 

Effects  of  Current,  Table 199 


Gains,  Buck-Arm 681 

Cross-arm 681 

Definitions 23 

Galvanized  Steel  Strand,  Specifica- 
tions for 251 

Galvanizing,  Definitions 23 

Hot,  Description  of 782 

Specification  for 784 

Gauge,  American  Wire,  Definition 

of 4 

Brown  &  Sharpe,  Law  of 196 

Gauges  of  Wire,  Comparison  of .  .  .  195 

Wire 195 

Gauss,  Definition 23 

German     Government     Report — 

Wood  Preservation 664 

Gilbert,  Definition 23 

Glass  Insulators 293 

Cementing  Together  Parts. . .  .  294 
Glazing  and  Firing  Porcelain  In- 
sulators   291 

Insulator,  Properties  of 293 

Globe   Strain,    Insulators,    Defini- 
tion    23 

Gradient,  Electric,  Definition 23 

Grading   Capacity   of    Suspension 

Insulators 311 

Graphical  Solution  of  Three-phase 

Transmission  Lines 479 

Graphite,  Definition 23 

Greek  Alphabet 57 

Grip,  Cable,  Definition 8 

Ground,  Definition 24 

Circuit,  Definition 24 

Connections,  Testing  of 433 

Effect  of,  Definition 24 

Pipe 429 

Return,  Definition 24 

Secondary 433 

Stub 162 

Water  Pipe 433 

Wires  on  Transmission  Lines.  411 

Grounding 428 

Devices 432 

of  LightningJProtective  Appa- 
ratus   409 

of  Transformer  Cases 433 

Gutta-Percha,  Definition 25 

Guys,  Anchor 704 

Guy  Anchor,  Locating  Foot  of 706 

Anchors,  Patented 284 

Anchor  Protection 706 

Attachments 701 

Clearance 709 

Guys,  Cross-arm .  709 

Guy,  Definition 25 

Fittings 701 

Insulation 709 

Guys,  Pole,  Definition 44 


[804] 


INDEX 


PAGE 

Guy  Rods 282 

Rods,  Specification  for ....  282-284 

Guys,  When  to  Use  on  Poles 695 

When  to  Use  Two  Guya 706 

Guy  Wire,  Definition 25 

Wire 212,  701 

Guying,  Calculation  of 557 

Corner  Poles 697 

Curved  Lines 697 

to  Iron  Poles 709 

Long  Spans 695 

Poles  on  Hills 701 

Straight  Lines 695 

Stub 701 

Terminal  Poles 695 

to  Tree 706 

H 

Hailstorms...                                 ..  767 

Hall  Effect,  Definitions 25 

Handling  of  Conrcete  Polea 141 

Hard-drawn,    Copper    Clad,    Steel 

Wire,  Specification  for 254 

Copper  Wire,  Definition 26 

Copper    Wire,    Specifications 

for 252 

Harmonic  Currents,  Definition.. .  .  26 
Harmonics,  Effects  of  Higher,  Defi- 
nition   29 

H.  B.  Curves,  Definition 25 

Heart  Rot 123 

Wood 582 

Heat,  Definition 31 

Mechanical      Equivalent     of, 

Definition 38 

Unit,  Definition 31 

Heating  Effects  of  Currents 200 

of  Current,  Table  of 202 

Heating  Test,  Regulators 385 

Transformers 350 

Heavy  Poles 685 

Height  of  Poles 681 

Henry,  Definition 31 

High  Frequency,  Definition 31 

Potential  Current,  Definition .  32 

Potential     Insulator,     Defini- 
tion    32 

Tension  Circuit,  Definition. . .  32 
Hollow  Concrete  Poles,  Method  of 

Manufacture 141 

Poles 141 

Horn  Arresters 409 

Horse-Power,  Definition 32 

Electric,  Definition 32 

Hour,  Definition 32 

Hot  Galvanizing,  Description  of . .  782 

Treatment,    Wood    Preserva- 
tion    602 

Waves 762 

Hydro-Electrio  System,  Definition  32 
Hysteresis,  Coefficient  of,  Defini- 
tion  11,32 

Definition 32 

Dielectric,  Definition 17 


PAGE 

Hysteretic  Cycle,  Definition 32 

Lag,  Definition 32 

Losses,  Transformers 329 


Ice  Storms 767 

Idaho  Cedar,  Specifications  for .  .  .  129 

Poles,  Dimensions  of 130 

Impedance  Coils,  Definition 32 

Components  of,  Definition.  .  .  11 

Definition 32 

Tests,  Induction  Regulators .  .  386 
Impressed    Electromotive    Force, 

Definition 33 

India-Rubber,  Definition 33 

Induced  Current,  Definition 33 

Electromotive  Forces,  Defini- 
tion   33 

M.  M.  F.f  Definition 33 

Voltage,  Transformers 331 

Inductance  Coil,  Definition 33 

Definition 33 

Distributed,  Definition 17 

Formulae  for 463 

Induction,  Definition 33 

Counter-Electromotive-Force 

of,  Definition 14 

Electrostatic,  Definition 20 

Magnetic,  Definition 33 

Mutual,  Definition 33,  39 

Regulators,  Description ...      .  379 

Self,  Definition 33 

Inductive  Capacity,  Specific,  Defi- 
nition    49 

Circuits,  Definition 33 

Reactance,  Definition 34,  45 

Reactance,  Solid  Wire,  Table 

of 229 

Reactance,     Stranded     Wire, 

Table  of 235 

Ingots,  Working  of 181 

Ions,  Electro  Negative,  Definition.  20 

Positive,  Definitions 20 

In-put,  Definition 34 

Installation  of  Fuse  Blocks 736 

Installation  of  Transformers 729 

Installing  Pole  Steps 687 

Instantaneous  Peak,  Definition ...  34 

Insulate,  Definition 34 

Insulated  Wires,  Definition 34 

Insulating  Joint,  Definition 34 

Varnish,  Definition 34 

Insulation,     Breaking     Down    of, 

Definition 7 

of  Guy  Wire 709 

Induction  Regulators,  Testing 

of 385 

Moisture-Proof ,  Definition ...  39 

Protection  of  Rubber 183 

Resistance,  Definition 34 

Rubber 181 

Transformers 334 

Transformer,  Testing  of 345 

Weatherproof 181 


[  805] 


INDEX 


PAGE 

Insulation,     Weatherproof,     Defi- 
nition        55 

Insulator  Cement 294 

Property  of 295 

Insulator  Characteristics,  Effect  of 

Different  Types  of  Pins  on . .   297 

Clays 289 

Electric,  Definition 34 

Failures 298 

Glazing,  Properties  of 293 

High-potential,  Definition 32 

Manufacture 291 

Petticoat,  Definition 42 

Pin,  Definition 35 

Pins,  Wood,  Specification  for 

272,  273 

Protection 301 

Strain,  Definition 50 

Suspension,  Calculated  Char- 
acteristics    308 

Suspension,    Effective    capac- 
ity    304 

Suspension,  Grading  Capacity 

of 311 

Suspension,  Voltage  Distribu- 
tion, Dry  Arc-over 311 

Suspension,  Voltage  Distribu- 
tion, Wet-Arc-Over 311 

Tests 299 

lor  Trees 713 

Triple  Petticoat,  Definition. .     53 

Insulators,  Ageing  of 298 

Cementing  together,  built-up .   294 

Composition 296 

Effect  of  Mechanical  Stress  on  296 
Electrical  Characteristics  of . .   297 

Glass 293 

Glass,     Cementing     together 

parts 294 

Installing  on  Cross- Arms 695 

Method  of  Attaching  to  Pins .   278 

Pin  Type 289 

Porcelain 289 

Porcelain,  Coloring  of  Glaze . .   291 

Porcelain,  Dry  Process 291 

Porcelain,  Glazing  and  Firing .   29 1 

Porcelain,  Wet  Process 291 

Strain 289 

Suspension 289 

Intensity,  Magnetic,  Definitions .  .     37 

Interleaved  Winding 323 

Internal  Inductance  of  Wire 247 

Iron  Core  Loss,  Definition 35 

Location  of  Ore 179 

and  Steel,  Location  of  Ore .  .  .    180 
or  Steel,  Magnetic  Fatigue  of, 

Definition 21 

and  Steel,  Reduction  of 180 

and  Steel,  Refining  of 180 

Loss,  Voltmeter 356 

Loss  Tests,  Induction  Regu- 
lators   386 

Poles,  Guying  to 709 

Wire,  Table  Physical  Constants  188 


PAGE 
Jackets,   or  Butt  Settings,  Wood 

Preservation 610 

Joints,  Britannia,  Definition 7 

Joint,  Insulating,  Definition 34 

Sleeve,  Definition 49 

Joule,  Definition 35 

Joule's  Law  of  Heating,  Definition     35 
Jumper,  Definition 35 


Kaolin,  Definition 35 

Kilo,  Definition 35 

Kilovolt,  Definition , 35 

Ampere,  Definition 35 

Kilowatt,  Definition 35 

Hour,  Definition 36 

Knife-Switch,  Definition 36 


Lagging  Current,  Definition 36 

Lag,  Hysteretic,  Definition 32 

Screws 279 

Screws,  Specification  for .  .  279-281 

Laminated  Core,  Definition 13,  36 

Lamination  of  Core,  Definition.  .  .      13 

Definition 36 

Law  of  the  Brown  &  Sharpe  Gauge  196 
of  Heating,  Joule's  Definition .     35 

Lead,  Definition 36 

Encased  Cable,  Definition 36 

Leading  Current,  Definition 36 

Leakage  Reactance,  Definition. ...     36 

Leg  of  Circuit,  Definition 36 

Lenz's  Law,  Definition 36 

Life  of  Poles,  Comparison  of  Pre- 
servatives     664 

Lightning  Arrester,  Definition ....      36 
Arresters,  Aluminum  Cell ....   403 

Arresters,  Compression 397 

Arresters,  Electrolytic 403 

Arrester  Grounds  (A-C) 433 

Arresters,  Grounding  of 409 

Arresters,  Installation  of 745 

Arresters,  Location  of 407 

Arresters,  Low  Equivalent .  .  .   397 

Arresters,  Multigap 397 

Arresters,  Multipath 406 

Arrester,  Single  Gap 404 

Phenomena 393 

Protective  Apparatus 396 

Rod,  Definition 36 

Lighting  System,  Direct  Current 

Series,  Description 440 

Line,  Capacity  of,  Definition .....       9 
Construction,      Specifications 

for 674-749 

Line  Hardware,  Carriage  Bolts .  .  .    279 

Cross-arm  Bolts 279 

Cross-arm  Braces 278 

Guy  Rods 282-284 

Lag  Screws 279 

Patented  Guy  Anchors 284 


[806] 


INDEX 


PAGE 

Line  Hardware,  Pole  Brackets 284 

Specification  for 279-284 

Washers - 279 

Line  Level  of  Pole  Line 685 

Loss  Tables,  Explanation  of. .   472 
Supports  at  Different  Levels, 

Formulae  for 529 

Terminals 720 

Wire  or   Conductor,   Sag   of, 

Definition 47 

Wire  Taps 720 

Lines  of  Force,  Definition 36 

of   Force,   Electrostatic,  Defi- 
nition       20 

of  Magnetization,  Definition. .      36 

on  Private  Property 722 

Links,  Fuse,  Definition 23 

Link  Fuses 420 

Live  Wire,  Definition 37 

Load,  Definition 37 

Loads,    Power-factors   of    Various 

Types 505 

Loading  of  Structural  Steel  Poles .  149 
of  Structural  Steel  Towers .  .  .  149 
Table,  Aluminum  Wire.Strand- 

ed,  Bare 541 

Table  of  Bare  Copper  Wire, 

Solid 539 

Table  of  Bare  Copper  Wire, 

Stranded 538 

Table,  Insulated  Copper  Wire  540 

Load-factor,  Definition 37 

Loblolly  Pine,  Cutting  of 118 

Logging  of 118 

Locating  the  Center  of  Distribu- 
tion    490 

Poles  on  Street 683 

Location  of  Aluminum  Ores 179 

of  Copper  Ore 177 

of  Iron  Ore 179 

of  Lightning  Arresters 407 

of  Steps  on  Poles 687 

and  Wiring  of  Lightning  Pro- 
tective Apparatus 407 

of  Wires  9n  Poles 722 

Lodge  Pole,  Pine  Poles,  Logging  of  122 

Where  Grown 122 

Logarithm,  Definition 37 

of  Numbers,  Common 59-83 

Logging,  Chestnut 112-114 

of  Loblolly  Pine 118 

of  Lodge  Pole  Pine  Poles ....    122 

of  Western  Red  Cedar 114 

of  Western  Yellow  Pine 119 

White      Cedar     and      Arbor 

Vitae Ill,  112 

Loop  Test,  Definition 37 

Loss,  Copper,  Definition 13 

Corona 484 

Losses,  Core,  Definition 13 

Low    Artificial    Pressure    System, 

Wood  Preservation 607 

Equivalent  Lightning  Arrest- 
ers    397 

Potential  System,  Definition..     37 


PAGE 
Lowry  Process  of  Wood  Preserva- 


601 


M 


Magnetic  Fatigue 337 

Fatigue,  Definition 37 

Fatigue  of  Iron  or  Steel,  Defi- 
nition       21 

Field,  Definition 22,  37 

Flux,  Definition 37 

Flux-Paths,  Definitions 37 

Magnetizing  Force,  Definition.  ...     38 
Magnetic  Induction,  Definition.  .  .     33 

Intensity,  Definition 37 

Saturation,  Definition 37 

Units,  Definition 38 

Magnetism,  Residual,  Definition.  .      46 
Magnetization,  Lines  of,  Definition     36 

Mains,  Definition 38 

Distributing,  Definition 18 

Supply,  Definition 50 

Three- Wire,  Definition 52 

Two-Wire,  Definition 53 

Manufacture  of  Glass  Insulators. .   293 

Insulators,  Porcelain 291 

Wire 181 

Wire,  Application  of  Rubber.    182 
Wire,    Protection   of   Rubber 

Insulation 183 

Wire,  Rubber  Insulation 181 

Wire,  Vulcanizing 182 

Wire,     Weatherproof    Insula- 
tion     181 

Wire,  Wire  Drawing 181 

Wire,  Working 181 

M.  M.  F.  Induced,  Definition 33 

Map,  The  Weather 756 

Mass,  Definition 38 

Matthiessen's    Standard   Conduc- 
tivity    190 

Maximum  Demand,  Definition ...      38 
Temperatures,        Table        of 

Monthly  Mean 768 

Maxwell,  Definition 38 

Mean  Current,  Definition 38 

Mean  Electromotive  Force,  Defi- 
nition       38 

Mechanical  Calculation  of  Trans- 
mission      and       Distribution 

Lines 523-559 

Mechanical   Equivalent   of   Heat, 

Definition 38 

Stress,  Effect  on  Insulators..   296 

Tests,  Insulators 301 

Megohm,  Definition 38 

Mho,  Definition 38 

Mensuration 102 

Messenger  Rope,  Definition 38 

Metal  Pins,  Types  of 274 

Wood  and  Porcelain  Pins ....   274 
Methods    of    Calculating    Trans- 
mission Line  Losses 464 

Method    of    Transposing    Trans- 
mission Lines 509 


[807] 


INDEX 


PAGE 
Metric  Weights  and  Measures  103, 104 

Microfarad,  Definition 38 

Microhm,  Definition 38 

Micrometer    Wire-Gauge,    Defini- 
tion      38 

Mil,  Definition 39 

Circular,  Definition 10 

Foot,  Definition 39 

Milli-Ampere,  Definition 39 

Definition 39 

Milli-Henry,  Definition 39 

Volt,  Definition 39 

Minimum  Temperature,  Table  of 

Monthly  Mean 769 

Mixed   Oils,    Wood   Preservation, 

Specification  for 628 

Mixture  of  Concrete  for  Concrete 

Poles 139 

Modulus  of  Elasticity,  Definition . .     39 
Moisture-Proof  Insulation,  Defini- 
tion      39 

Molding,  Abrasion 713 

of  Concrete  Poles 140 

Moment  of  Inertia  Formulae,  Table 

of 525 

Motion,  Clockwise,  Definition.  ...      10 
Multiple  Connection,  Definition. . .      12 

Circuit,  Definition 10,39 

Multi-gap  Lightning  Arresters..    .   397 

Multiple  Pipe  Grounds 429 

Series  Circuit,  Definition ...  .  39 
Multi-path  Lightning  Arresters.  .  406 
Mutual  Inductance,  Coefficient  of, 

Definition 11 

Induction,  Definition 33,  39 

N 

Natural  Trigonometric  Functions, 

Tables  of 85-91 

Needle  Gaps,  Table  of  Sparking 

Distances 513 

Negative  Conductor,  Definition...  39 

Feeders,  Definition 39 

Neutral  Conductor,  Definition 39 

Feeder,  Definition 39 

Non-Conductor,  Definition 39 

Inductive  Resistance,  Defini- 
tion   40 

Normal  Current,  Definition 40 

Numbering  of  Poles 683 


Obstacles,    Clearing   of,    by    Pole 

Line 685 

Oersted,  Definition 40 

Ohm,  Definition 40 

Ohm's  Law,  Definition 40 

Ohmic  Resistance,  Definition 40 

Drop,  Definition 40 

Oil  for  Preserving  Wood . 586 

Preservatives,  Comparison  of.   595 
Transformer,  Specifications  of  364 


PAGE 

Oil-break  Switches 417 

Duct,  Transformer 324 

Immersed  Fuse 425 

Open  Circuit,  Definition 10, 41 

Tank  Plants,  Description  of .  .  64 1 
Tank  Treatment,  Creosote  Oil  655 
Tank  Treatment,  Creosote 

and  Zinc  Chloride 659 

Tank  Treatment,  Crude    Pe- 
troleum     657 

Tank     Treatment,     of     Pole 

Butts,  Specification  for ....   640 
Tank     Treatment,     Western 

Yellow  Pine 655 

Tank  Treatment,  Wood  Pres- 
ervation          607 

Tank  Treatment  Zinc  Chlo- 
ride    658 

Operation,  Transformer 366 

Ore,  Location  of  Aluminum 179 

Location  of  Copper 177 

Iron 179 

Oscillations  and  Surges,  Causes.  .  .   396 
Oscillatory  Current,  Definition.. .  .     41 

Outdoor  Sub-stations 163 

Overhead  Conductor,  Definition .  .     41 
Over-Potential  Test,  Transformers  350 


Page  Effect,  Definition 41 

Painting,  Cross-Arms 690 

Poles 681 

Pancake  Winding 323 

Paper  Cable,  Definition 41 

Paraffine,  Definition 41 

Parallel  Circuit,  Definition 10 

Connecting  of  Transformers . .  368 

Patented  Guy  Anchors 284 

Steel  Poles 147 

Peak,  Definition 41 

Load,  Definition 41 

Percentage  Conductivity 190 

of  Wire,  Definition 41 

Periodic  Function,  Definition 41 

Periodicity,  Definition 41 

of,  Alternation,  Definition  of.  4 

Permittance,.  Definition 41 

Petroleum  Oil  for  Wood  Preserva- 
tion   594 

Petticoat  Insulator,  Definition. ...  42 

Phase  Angle,  Definition 43 

Definition 42 

Difference,  Definition 43 

Phenomena,  Lightning 393 

Physical  Data 102 

Pin  Threading,  Standard 272 

Type  Insulators 289 

Pins,  Effect  of  High  Voltage  on.  . .  297 

Combination 274 

Definition 43 

Effect  of  Different  Types  on 

Insulator  Characteristics. . .  297 

Fitting  in  Cross-arms 695 

Insulator 270 


[808] 


INDEX 


PAGE 
Pins,  Method  of  Attaching  to  Cross- 

Arms 278 

Method  of  Attaching  Insula- 
tors to 278 

Preservation  of 297 

Specification  for  Wood  Insu- 
lator   272 

Wood 270-272 

Pine  Cross-Arm,  Creosoted,  Speci- 
fications for 637 

Cross-Arms,  Specifications  for 
Creosoting 638 

Cross-Arms,  Specifications  for 
Creosoted 270 

Western  Yellow,  Annual  Serv- 
ice Charge  Wood  Preserva- 
tion   660 

Western  Yellow,  Comparative 
Cost  of  Treatment 661 


Western  Yellow,  Treated  with 

Creosote 

Western  Yellow,  Treated  with 


655 
658 


Crude  Petroleum 

Western  Yellow,  Treated  with 

Zinc  Chloride 659 

Pipe  Grounds 429 

Multiple 429 

Resistance  of 429 

Pipe,  Water,  Grounds 433 

Plane  Vector,  Definition 43 

Plants  for  Wood  Preservation ....  597 

Plating,  Zinc,  Definition 57 

Platinum,  Definition 44 

Plumbago,  Definition 44 

Poles,  Artificial  Foundation  for.  . .  687 

Pole,  Attaching  Braces 690 

Brackets 284 

Poles,   Calculation  of   Dead  End 

Loading 556 

Calculation  of  Rotted 553 

Chestnut,  Dimensions  of 126 

Concrete  Molding  of 140 

Creosoted    Yellow   Pine,    Di- 
mensions of 134 

Crib  Bracing  for 686 

Eastern  White  Cedar,  Dimen- 
sions of 127 

Pole,  Fitting  Cross-Arms  to 690 

Guys,  Definition 44 

Guying 695 

Poles,  Heavy 685 

Height  of 681 

Hollow  Concrete 141 

Hollow  Concrete,  Method  of 

Manufacture 141,  142 

Idaho  Cedar,  Dimensions  of. .  130 

Pole-Line  Arresters 397 

Line  Level 685 

Poles,  Located  in  Rock 687 

Locating  on  Street 683 

Location  of  Curb  Line 685 

Location  of  Wires 722 

Pole  Numbering 683 

Poles,  Painting  of 681 

Preservative  Treatment  of .    .  561 


PAOB 

Poles,  Protection  of 687 

Red  Cedar  Poles,  Dimensions 

of 130 

Sawed  Red  Wood,  Dimensions 

of 132 

Seasoning 565 

Setting  of 685 

Setting  in  Quick-Sand 687 

Settings,  Table  of 685 

Solid  Concrete 135, 1 36 

Spacing  of 683 

Pole  Specifications 125 

Poles,  Steel 145 

Tubular,  Table  of 146 

Pole  Steps 281 

Definition 44 

Installing 687 

Location  on  Poles 687 

Specification  for 281,  282 

Poles  to  be  Stepped 687 

Storing 566 

Pole     Strength,     Calculation     for 

Bends  in  line 557 

Stresses,  Calculation  of 549 

Poles,  Structural  Steel 148 

Pole  Treating  Plants,  Open  Tank, 

Description  of 641 

Treatment.Comparative  Costs  661 
Treatment,  Western  Red  Ce- 
dar, Creosote 661 

Treatments,      Western      Red 
Cedar,    Creosote  and   Zinc 

Chloride 664 

Treatment,    Western    Yellow 

Pine,  Open  Tank 655 

Treatments,      Western      Red 

Cedar,  Crude  Petroleum.  .  .  663 
Treatments,   Western  Yellow 

Pine,  Crude  Petroleum ....  658 
Treatments,   Western  Yellow 

Pine,  Chloride 659 

Treatments,     Zinc     Chloride, 

Western  Red  Cedar 663 

Poles,  Trimming 681 

Tubular  Steel 147 

Pole  Tvpe  Regulators 384 

Wiring 720 

Wiring  for  Arc  Lamps 748 

Poles,  Wiring  of  Corner 720 

Pole     Wiring     for     Incandescent 
Lamps . . . 


749 
130 


Poles,  Western  Cedar,  Dimensions 

of 

Western  White  Cedar  Poles, 

Dimensions  of 130 

Wood Ill,  135 

Yellow,  Pine,  Dimensions  of .  .    133 

Polyphase  Circuits,  Definition 44 

Currents,  Definition 15 

Definition 44 

Induction     Regulators,     De- 
scription    382 

Systems,    Connecting   Single- 
Phase  Load  to 498 

Transmission,  Definition 4^ 


[809] 


INDEX 


PAGE 

Polyphase  Transformers,  Descrip- 
tion     367 

Porcelain,  Definition 44 

Insulators 289 

Insulators,  Cementing  together 

Parts 294 

Insulator  Clays 289 

Insulators,  Coloring  of  Glaze .   291 

Insulators,  Dry  Process 291 

Insulators,  Glazing  and  Firing  291 

Insulator  Manufacture 29 1 

Insulators,  Properties  of  Glaz- 
ing    293 

Insulators,    'Relative    Advan- 
tage of  Wet  and  Dry  Process  292 

Insulators,  Wet  Process 291 

Wood  and  Metal  Pins 274 

Positive  Wire,  Definition 44 

Potential,  Drop  of,  Definition. ...      18 

Electric,  Definition 44 

Electrostatic,  Definition ...          20 

Energy,  Definition 44 

Regulators,  Definition  of . . .       319 
Polarity  Test,  Transformers.  .  . .       362 
Potential,  Traveling  Waves  of.  .       394 
Power,  Alternating  Current,  Defi- 
nition of 4 

Apparent,  Definition  of 5 

Definition 44 

Circuits,  Definition 44 

Factor,  Definition 44 

Factors,  Resultant 505 

Factor  Transformers 340 

Factors  of  Various  Types  of 

Load 505 

Preservation  of  Pins 297 

Preservative 578 

Agents 585 

Treatment  of  Cross-Arms.  ...   561 

of  Wood  with  Oils 586 

Preservatives,  Comparison  of  Oil. .   595 
Preservative  Treatment  of  Poles. .   561 

Preserving  Wood  with  Salts 594 

Primary,  Definition 44 

Coil  of  Transformer,   Defini- 
tion      44 

Currents,  Definition 45 

Electro-motive  Force,  Defini- 
tion  

Processes  for  Wood  Preservation . . 
Production  of  Coal-Tar  Creosote. . 

Copper  Clad  Billets 

Water-Gas  Creosote. 


45 
596 
587 
180 
592 
293 
214 

Wire  Materials,  Table  of 537 

Property  of  Insulator  Cement ....  295 

Protection  of  Insulators 301 

Poles 687 

Rubber  Insulation 183 

Pulsating  Current,  Definition 45 


Properties  of  Insulator  Glazing .  .  . 
Special  Steel  Strands,  Table  of 


Quadrature,  Definition 45 


PAGE 

Quantity,  Electric,  Definition 45 

of  Oil  Necessary  for  Creosoted 

Pine  Poles 635 

Vector,  Definition 53 

Quarter  Phase,  Definition 45 

System,  Definition 45 

Quick-Sand,  Setting  Poles  in 687 


Radian,  Definition 45 

Per  Second,  Definition 45 

Radius  of  Gyration,  Table  of 525 

Railway  System,  Direct  Current, 

Description  of 439 

Method  of  Calculating 466 

Rain  Storms 766 

Ratio  of  Transformation,  Defini- 
tion      45 

Transformers 332 

Transformer,  Test  of 361 

Reactance,  Capacity,  Definition .  .        9 

Coils,  Definition  of 319 

Drop,  Transformers 360 

Effective,  Definition 19 

Factor,  Definition 45 

Inductive,  Definition 34, 45 

Leakage,  Definition 36 

Reactive  Drop,  Definition 45 

Electromotive   Force,   Defini- 
tion      46 

Factor,  Definition 46 

Reactors,  Definition  of 319 

Red  Cedar  Poles,  Dimensions  of .  .    130 
Specification  for 129 

Reduction  of  Aluminum  Ore 178 

Copper 177 

Iron  and  Steel 180 

Steel  and  Iron 180 

Refining  of  Aluminum  Ore 179 

Copper 177 

Iron  and  Steel 180 

Steel  and  Iron 180 

Regulation,  Definition 46 

of  Induction  Regulators 387 

of  Regulators 501 

of    Regulators,     Single-Phase 

System 501 

of    Regulators,    Three-Phase, 

Four-Wire  System 503 

of    Regulators,    Three-Phase, 

Three- Wire  System 502 

of      Regulators,      Two-Phase 

System 502 

Transformer 336 

Transf ormer  Calculation  of. ..  498 
of  Transformers,  Test  of 361 

Regulator  Capacity,  Calculation  of  503 

Regulators,  Induction,  Description  379 

Pole  Type 384 

Polyphase  Induction,  Descrip- 
tion     .  382 

Potential,  Definition  of 319 

Regulation  of 387,  501 


[810] 


INDEX 


PAGE 

Regulators,  Regulation  of,  Single- 
Phase  System 501 

Regulation    of,    Three-Phase, 

Four-Wire  System .   503 

Regulation    of,    Three-Phase, 

Three- Wire  System 502 

Regulation  of  Two-Phase  Sys- 
tem    502 

Test  of 385 

Voltage 501 

Reinforced  Concrete  Poles 135 

Reinforcing  Wires 721 

Relative  Advantage  of  Wet  and 
Dry  Process  Porcelain  In- 
sulators   292 

Conductivity 190 

Conductivity,  Table  of 191 

Resistance,  Table  of 191 

Reluctance,  Definition 46 

Residual  Magnetism,  Definition. . .     46 

Resin,  Definition 46 

Resistance,  Dielectric,  Definition..      17 

Definition 46 

Effective,  Alternating  Current  205 


Effective,  Definition ........ 

Equivalent,  Definition 

Measurements,  Transformers 


19 
21 
357 
40 


Non-inductive,  Definition ... 

Ohmic,  Definition 40 

of  Pipe  Grounds 429 

Relative,  Table  of 191 

Secondary ,  Definition 48 

Specific 189 

Specific,  Definition 49 

Specific,  Table  of 191 

Tests,  Induction  Regulators. .   386 

Track,  Table  of. 251 

Transformer  Insulation 345 

Units  of 189 

Units,  Comparison  of 189 

of  Wires,  Solid,  Table  of 221 

of  Wire,  Stranded,  Table  of .  .  222 

Resistivity,  Definition 46 

Resonance,  Definition 47 

Resultant  Load  on  Wire,  Formulae 

for 527 

Magnetic  Field,  Definition ...     47 

Power- Factors 505 

Resuscita  tion  f rom_Electric  Shock .   789 
Right  Handed  Rotation,  Definition     47 

Rights-of-Way 683 

Back- Yard 683 

Street . 683 

Ring  Rot 124 

Shakes 124 

Rock,  Setting  Poles  In 687 

Rods,  Guy 282 

Rod,  Lightning,  Definition 36 

Rods,  Specification  for  Guy 282-284 

Root-Mean-Square     or     Effective 

Value,  Definition 47 

Rope,  Messenger,  Definition 38 

Rotation,    Right-Handed,    Defini- 
tion      47 

Rotting  of  Wood,  Causes  of 583 


PAGE 
Rubber  Compound,  Application  of  182 

India,  Definition 33 

Insulation 181 

Insulation,  Protection  of 183 

Vulcanizing 182 

Rules  for  Resuscitation  from  Elec- 
tric Shock 789 

Running  Wires  Through  Trees..  .  .   713 
Riiping,  Process  of  Wood  Preserva- 
tion   601 

Rutgers  Process  of  Wood  Preserva- 
tion    600 


Saddle  Bracket,  Definition 47 

Safety  Fuse,  Definition 47 

Sag   of   Conductor  or   Line   Wire 

Definition 47 

Copper  Wire 714 

Problems,  Solution  of 524 

Salts,  for  the  Preservation  of  Wood  594 

Sap-Wood 582 

Saturation,  Magnetic,  Definition .  .     37 
Sawed  Red  Wood  Poles,  Dimen- 
sions of 132 

Specification  for 131 

Scott  Transformation- Vector  Anal- 
ysis   378 

Screws  Lag 279 

Specification  for  Lag 279-281 

Season  Checks 123 

Seasoning  Cross- Arms 565 

Poles 565 

Time  Required  for 574 

Secondary  Ampere-Turns,  Defini- 
tion      47 

Coil  of  Transformer- Definition 

of 47 

Connections,     Single  -  Phase, 

Two- Wire  System 443 

Connections,        Three-Phase, 

Four- Wire  Systems 450 

Connections,        Three-Phase, 

Three-Wire,  Description ...   448 
Connections,      Two  -  Phase, 

Four-Wire  System 445 

Connections,      Two  -  Phase, 

Three- Wire  System 445 

Currents,  Definition 47 

Definition 47 

Grounds 433 

Resistance,  Definition .  .  : 48 

Winding,  Definition 48 

Wires,  Stringing  of 729 

Secondaries,  Grounding  of 433 

Section  Modulus,  Table  of 525 

Self-Inductance,      Coefficient     of, 

Definition  of 11 

Induction,  Definition 33-48 

Induction,  Solid  Wires,  Table 

of 223 

Induction,     Stranded     Wire, 

Table  of 225 

Series  A.  C.  System,  Calculation  of  482 


[811] 


INDEX 


PAGE 
Series  A.  C.  system,  Description  of  450 

Series  Circuit,  Definition 10, 48 

Connection,  Definition 12 

Direct        Current        System, 

Method  of  Calculating 469 

Distribution,  Definition 48 

Lighting  System,  Direct  Cur- 
rent, Description  of 440 

Lighting  Transformers 378 

Multiple  Circuit,  Definition .  .     48 

Service  Wires,  Definition 48 

Setting  Poles 685 

in  Quick-Sand 687 

in  Rock 687 

Shearing  Stress  Formulae 523 

Shell  Type  Transformers 320 

Shellac,  Definition 48 

Sherardizing,  Description  of 784 

Shock,  Resuscitation  from  Electric  789 

Short  Circuit,  Definition 48 

Simple  Harmonic  Electro-Motive- 
Force,  Definition 48 

Periodic  Current,  Definition. .      15 

Sine,  Definition 48 

Law,  Definition 48 

Single  Gap  Lightning  Arrester 40-4 

Single-Phase,  Calculation  of  Reg- 
ulator Capacity 503 

Definition 48 

Load  Connected  to  Polyphase 

System 498 

System,  Definition 443 

System,  Regulation  of  Regu- 
lators    501 

System,  Three- Wire,  Descrip- 
tion of 443 

Three- Wire,  System,  Calcula- 
tion of 477 

Transmission,     Vector     Dia- 
grams     454 

Two-Wire  Systems,   Calcula- 
tion of 474 

Two-Wire  Systems,   Descrip- 
tion of 443 

Single-Pole  Cut-out  Definition. ...     49 
Sinusoidal     Alternating     Electro- 

Motive-Forces,  Definition 49 

Sinusoidal  Curve,  Definition 49 

Skin  Effect 205 

Definition 49 

Factors,  Table  of 207 

Sleet 767 

Data,  Table  of 778 

Sleeve,  Connecting,  Definition 12 

Joint,  Definition 49 

Splicing,  Definition 49 

Snow  Storms 766 

Soft  Drawn  Copper  Wire,  Defini- 
tion      49 

Solid  Concrete  Poles 135,  136 

Solution  of  Sag  Problems 524 

Spacing  of  Poles 683 

Sparking  Distances 512 

Special  Cross-Arms 270 

Galvanized  Strand. .  .  .  212 


PAGE 

Special  Steel  Strands,  Table  of .  .  .   214 
Strands,  Table  of  Extra  Gal- 
vanized    213 

Specific  Conductivity 190 

Definition 49 

Specific  Inductive  Capacity,  Defi- 
nition      49 

Resistance 189 

Resistance,  Definition 49 

Resistance,  Table  of 191 

Spelter,  Definition 49 

Specifications  for  Aerial  Line  Con- 
struction  674-749 

for         Aluminum         Cables, 

Weatherproof  Insulated ...   257 
for  Aluminum  Wire,  Weather- 

Proof  Insulated 257 

Analysis  Coal  Tar  Creosote .  .    624 
Analysis  of  Mixed  Oils,  Wood 

Preservation 629 

Analysis     of     Water-Gas-Tar 

Creosote 630 

for  Bare  Aluminum  Wires 257 

for  Bare,  Hard-Drawn  Copper 

Wire 252 

for  Carriage  Bolts 279-281 

for  Chestnut  Poles 125 

for   Circular  Loom  Covered, 

Tree  Wire 259 

for  Coal-Tar  Creosote 621 

for  Copper  Cables,  Weather- 

Proof  Insulated 251 

for     Creosoted     Pine    Cross- 
Arms 270,637 

for  Creosoted  Pine  Poles 634 

for    Creosoted    Yellow    Pine 

Poles 134 

for    Creosoting    Pine    Cross- 
Arms 638 

for  Creosoting  Pine  Poles ....   635 

for  Cross- Arm  Bolts 279-281 

for  Cross- Arm  Braces 279 

for  Eastern  White  Cedar  Poles  127 
for  Galvanized  Steel  Strand ..   251 

for  Galvanizing 784 

for  Guy  Rods 282-284 

for  Hard-Drawn  Copper  Clad, 

Steel  Wire 254 

for  Idaho  Cedar 129 

for  Lag  Screws 279-281 

for  Mixed  Oil,  Wood  Preserva- 
tion   628 

Oil  for  Brush  Treatment 633 

for  the  Open-Tank  Treatment 

of  Pole  Butts 640 

for  Pole  Steps 281,  282 

for  Red  Cedar 129 

for  Sawed  Red  Wood 131 

Transformers 363 

Transformer  Oil 364 

for  Tree  Wire 259 

of  Untreated  Cross-Arms 267 

for  Washers 279-281 

f or  Water-Gas-Tar  Creosote. .   629 
for  Weatherproof  Copper  Wire  251 


1812] 


INDEX 


PAGE 

Specifications  for  Western  Cedar  .    129 
for  Wood  Insulator  Pins .  .  272,  273 

Wood  Poles 125 

Wood  Presei  ration,  Auxiliary  630 

for  Yellow  Pine  Poles 133 

Sphere  Gaps 514 

Sparking  Distances,  Table  of .   514 

Splicing  Sleeve,  Definition 49 

Structural  Steel  Poles 159 

Wires 715 

Split  Phase,  Definition 49 

Spray  and  Brush  Discharge,  Defi- 
nition of 7 

Spreader  Brackets 720 

Square  Mil,  Definition 49 

Stampings,    Transformer,    Defini- 
tion      52 

Standard  Conductivity,  Matthies- 

sens' 190 

Frequencies,  Definition 441 

Pin  Threading 272 

Steel  Strands,  Table  of 212 

Star-Three-Phase  System,  Defini- 

ti9n 50 

Static  Discharge,  Definition 50 

Electricity,  Definition 50 

Steel  Cross-Arms 270 

and  Iron,  Reduction  of 180 

and  Iron,  Refining  of 180 

Poles,  Function  of  Bracing. . .   155 

Poles,  Patented 147 

Poles  and  Towers 145 

Poles  and  Towers,  Comparison 

of  Strength 159 

Poles,  Tubular 147 

Reinforcing,  Concrete  Poles . .    136 
Strand,  Galvanized,  Specifica- 
tions for 251 

Towers 145 

Towers,  Function  of  Bracing .    155 

Towers,  Structural 148 

Tubular  Poles,  Table  of 145 

Wire,  Stranded,  Table  of  load- 
ing    536 

Wire,  Table  of  Physical  Con- 
stants      187 

Steps,  Pole 281 

Pole,  Definition 44 

Specification  for  Pole 281,  282 

Step-Down    Transformer,    Defini- 
tion       50 

SteprUp  Transformer,  Definition . .     50 

Storing  Cross-Arms 566 

Poles 566 

Storm  Movements 755 

Strain,  Definition 50 

Insulators 289 

Insulator,  Definition 50 

Insulators,  Globe,  Definition.     23 
Strand,  Galvanized  Steel,  Specifi- 
cations for 251 

Stranded  Conductor,  Definition. . .     50 

Strands,  Special  Galvanized 212 

Table  of  Standard  Steel 212 

Wire..,  .   197 


PAGE 

Stray  Currents,  Definition 50 

Field,  Definition 50 

Street  Crossings 683 

Rights-of-Way 683 

Strength  of  Concrete 139 

Current,  Definition 50 

Rotted  Poles,  Calculation  of .  .  553 

Timber,  Table  of 524 

Stress,  Definition 50 

Stresses  on  Cross-Arms,  Calcula- 
tion of 547 

in  Poles,  Calculation  of 549 

Structural  Steel  Poles 148 

Failure  of 151 

Loading  of 149 

Towers 148 

Towers,  Failure  of 151 

Towers,  Loading  of 149 

Structure  of  Wood 578 

Stub,  Ground 162 

Guying 701 

Submarine  Cable,  Definition 8 

Sub-Stations,  Outdoor 163 

Surface  Density,  Definition 50 

Surges,  clue  to  Internal  Conditions .  396 

Lightning •. 

Surges  and  Oscillations,  Causes . 
Surging  Discharge,  Definition... 
Surgings,  Electric,  Definition . . . 

ftllYV^        \Tftf^+^^        Ttrv£v»l4.«^^. 


393 
396 
50 
50 
53 
50 
289 
308 


Sum,  Vector,  Definition. 

Supply  Mains,  Definition , 

Suspension  Insulators 

Calculated  Characteristics . 

Capacity 304 

Effective  Capacity 304 

Voltage  Distribution 302 

Voltage  Distribution  Dry  Arc- 
Over 311 

Voltage  Distribution  Wet  Arc- 
Over 311 

Switches 413 

Air-Break 413 

Switch,  Automatic,  Definition  of . .       6 

Switches,  Oil-Break 417 

Switch,  Time,  Definition 52 

Synchronism,  Definition 50 

Synchroscope,  Definition 51 

Series    System,     Direct    Current, 

Thury,  Description  of 440 

Systems  of  Distribution 722 

System,  Low  Potential,  Definition .     37 

Quarter-Phase,  Definition 45 

Star  Three-Phase,  Definition.     50 
Three- Wire,  Definition 52 


Table  of  Absorption  of  Creosote, 

Western  Red  Cedar .  . .  662 
Air  Density,  Correction 

Factor  487 

Aluminum  Wire,  Physical 

Constants  185 

Aluminum  Wire,  Special 

Sizes 247 


[813] 


INDEX 


PAGE 

Table   of  Annual  Service  Charge, 

Western  Yellow  Pine..  660 
Average  Life  of  Poles...  672 
B.  &  S.  Gauge,  Cross-Sec- 
tion Area  of  Wires....  196 
B.  &  S.  Gauge,  Diameter 

of  Wire  196 

Barometric  Corrections...  783 
Bending  Moment  Formulae  526 
Breaking  Strength  of 

Wire,  Solid 215 

Breaking  Strength  of 

Wires,  Stranded 216 

Capacity,  Solid  Wire....  226 
Capacity  of  Stranded  Wire  228 
Charging  Current,  Solid 

Wire  238 

Charging  Current, 

Stranded  Wire 244 

Circumferences  and  Areas 

of  Circles 95-99 

Comparative  Costs  of 

Preservation        Western 

Yellow  Pine 661 

Comparative  Wire  Gauge.  195 

Conversion  102-104 

Copper  Clad  Wire,  Phys- 
ical Constants  186 

Copper  Wire,  Physical 

Constants  184 

For  Correcting  Wind 

Velocities 781 

Cost  of  Treating  Timber.  674 
Current  Carrying  Capacity 

of  Wire 204 

Decimal  Equivalents 94 

Deflection  Formulae 526 

Diameters  of  Wire,  Solid.  217 
Diameters  of  Wire, 

Stranded  218 

Extra  Galvanized  Special 

Strands  213 

Fusing  Effects  of  Currents  199 
Green  Weights,  Loblolly 

Pine 576 

Heating  Effects  of  Current  202 
Inductive  Reactance,  Solid 

Wire  229 

Inductive  Reactance, 

Stranded  Wire 235 

Iron  Wire,  Physical  Con- 
stants    188 

Line  Loss,  Explanation  of  472 
Loading,  Aluminum  Wire, 

Stranded  Bare 541 

Loading,  Bare  Copper 

Wire,  Solid  539 

Loading,  Copper  Wire, 

Solid,  Insulated 540 

Loading,  Copper  Wire, 

Stranded,  Bare 538 

Logarithms  of  Numbers.  .  59-83 
Maximum  Recorded  Wind 

Velocities 772 


PAGE 
Table     of    Moment     of     Inertia 

Formula?     525 

Monthly     Mean     Maximum 

Temperatures     768 

Monthly     Mean     Minimum 

Temperature    769 

Natural     Trigonometric 

Functions    85-91 

Number      of      Days      with 

Dense  Fog 776 

Number  of  Days  Maximum 
Wind      Velocity      Above 

40    Miles 774 

Number     of     Days     with 
Minimum      Temperature 

Below  Zero 771 

Number      of      Days      with 
Temperature    Above    90 

Degrees    770 

Number   of   Thunderstorms  775 
Oil      Preservatives,      Com- 
parison         595 

Physical    Constant,     Alum- 
inum   Wire 185 

Physical  Constants,  Copper 

Clad  Wire 186 

Physical  Constants,  Copper 

Wire     184 

Physical     Constants,     Iron 

Wire     188 

Physical     Constants,     Steel 

Wire     187 

Pole    Settings 685 

Poles   Treated   with  Differ- 
ent Preservatives   .  .  .666-667 
•  Pole  Treatment,  Western 

Yellow  Pine.  .  .  .655-56-58-59 
Power  -  Factors,       Various 

Types  of  Loads 506 

Properties,    Wire    Material   537 

Radius    of    Gyration 525 

Relative     Conductivity....    191 

Relative    Resistance 191 

Resistance  of  Wire,   Solid.    221 
Resistance        of        Wire, 

Stranded    222 

Sag    of    Annealed    Copper- 
Line    Wire 714 

Seasoning,    Arbor   Vitae.  .  .    576 

Seasoning    Chestnut 575 

Seasoning,  Loblolly  Pine.  .    577 
Seasoning,       Wester      Red 

Cedar      575 

Seasoning,  Western  Yellow 

Pine      574 

Section  Modulus 525 

Self-induction,    Solid    Con- 
ductors         223 

Self-Induction,        Stranded 

Wire     225 

Skin  Effect  Factors 207 

Sleet  Data 778 

Sparking       Distances, 
Needle  Points 513 


[814] 


INDEX 


PAGE 

Table    of    Sparking    Distances, 

Sphere    Gaps 514 

Special    Steel    Strands....    214 

Specific    Resistance 191 

Standard    Steel    Strands..    212 

Steel    Tubular    Poles 146 

Steel  Wire,  Physical  Con- 
stants    187 

Stranded  Steel  Wire,  Load- 
ing of 536 

Strength    of    Timber 524 

Temperature  Coeffi- 
cients   192-194 

Track    Resistance 251 

Treated    Poles,    Length    of 

Life     668-670 

Weights    of    Wire,    Solid..    219 
Weights  of  Wire,  Stranded  220 

Tap,    Definition 51 

Taps   to   Line   Wire 72u 

Tangent,    Definition 51 

Temperature,    Absolute,    Defini- 
tion   of 3 

Coefficient      191-193 

Coefficient,    Definition  ....      51 
Coefficient,    Tables    of..  192-194 

Definition     51 

Maximum,      Table      of 

Monthly    Mean 768 

Minimum  Monthly  Mean.  .    769 

Transformers     334 

Tension   Formulae 523 

Terminals  of  Line  Wire 720 

Terminal    Voltage,    Definition..      51 

Tertiary    Coils 382 

Test,      Electrical      Insula- 
tors       299-301 

Induction     Regulator 385 

Loop,   Definition 37 

Mechanical    Insulators....    301 

Voltage-Measuring    of  ....    349 

Testing  of  Ground  Connections  433 

of    Insulators     299 

Transformer    345 

Thermometric      Scale,      Fahren- 
heit,   Definition 21 

Three-Phase,    Definition 51 

Four-Wire  System,  Calcu- 
lation of  Regulator  Ca- 
pacity    504 

Four-Wire  System,  De- 
scription    448 

Four-Wire     System,     Regu- 
lation   of    Regulators .  .  .    503 
System,    Calculation    of .  .  .    478 

Systems,     Definition 445 

System,  Vector  Diagram.  .    457 
Three-Wire   System,    Calcu- 
lation   of    Regulator    Ca- 
pacity         504 

Three-Wire  System,  De- 
scription    445 

Three-Wire  System,  Regu- 
lation of  Regulators.  .  .  502 


PAGE 

Three-Phase  Transformer,   Defi- 
nition         52 

Three-Wire,       Edison       System. 

Method    of    Calculating.    469 

Mains,    Definition 52 

Single-Phase     System,     De- 
scription   of 443 

System,    Definition 52 

System,    Edison.      Descrip- 
tion        440 

Three-Phase     System,     de- 
scription         445 

Two-Phase       System,       de- 
scription    of 443 

Thunderstorms    764 

Table  of  Total  Number.  .  .    775 
Thury     Direct     Current     Series 

System,    Description   of 440 

Tie   Wires 714 

Definition     52 

Time-Constant    of   Circuit,    Def- 
inition          52 

Required  for  Seasoning.  .  .    574 

Switch,    Definition 52 

Timber,   Table  of  Strength....    524 

Torsion    Formulae 524 

Towers,  Flexible 160 

Steel 145 

Structural    Steel 148 

Track    Resistance,    Table   of .  .      251 

Transformers,    Ageing    of....      321 

Air-Core,  Definition  of .  .  .  3 

Auto,    Definition    of 319 

Balancer,     Definition ....        52 
Capacity,    Calculation   of.      494 

Cases    324 

Cases,    Grounding  of 433 

Characteristics     345 

Coils     321 

Constant    Current,    Defini- 
tion   of 319 

Construction    319 

Copper  Losses 330 

Copper    Loss    Test 359 

Cores    320 

Core,     Ageing     of,     Defini- 
tion of 3 

Core    Loss    Test 355 

Core    Type 320 

Cruciform   Type 321 

Definition     52 

Design    333 

Eddy  Current  Losses 329 

Efficiency 335 

Efficiency,    Calculation    of.    500 

Equations    327 

Exciting   Current    330 

Exciting    Current    Test...    355 

Heating  Test 350 

Hysteretic  Losses    329 

Induced  Voltage 331 

Installation  of 729 

Insulation    334 

Insulation-Testing  of    ....    345 


[815] 


INDEX 


PAGE 

Transformers,   Method  of  Erec- 
tion         733 

Oil   Duct    324 

Oil   Specifications    364 

Operation     366 

Over  Potential  Test 350 

Parallel,   Connecting  of .  .  .    368 

Polarity    Test    362 

Polyphase     367 

Power-factor    340 

Primary     Coil     of,     Defini- 
tion          44 

Ratio    332 

Ratio,  Test  of 361 

Reactance   Drop    360 

Regulation      336 

Regulation,    Calculation    of  498 

Regulation,   Test   of 361 

Resistance    Measurements.    357 

Temperature    334 

Testing     345 

Three-Phase,    Definition...      52 
Scott,    Vector    Analysis...    378 
Secondary    Coil   of,    Defini- 
tion           47 

Series    Lighting    378 

Shell    Type    320 

Specifications     363 

Stampings,  Definition  ...  52 
Step-Down,  Definition  ...  50 

Step-Up,    Definition    50 

Transformation,   Ratio   of,   Def- 
inition          45 

Transmission    Circuit,    Electric, 

Definition     .  ." 52 

Constant  Voltage    511 

Economics   of    506 

Electric-Definition     52 

Line  Calculation,  Effect  of 

Charging  Current  ....  460 
Line  Calculation,  Formulae  462 
Line,  Choice  of  Voltage.  .  484 
Line,  Electric  Charges  on, 

Causes    393 

Lines,      Grounding     Wires 

on     411 

Line    Losses,     Methods    of 

Calculating     464 

Line    Transposition    509 

Polyphase,  Definition  ....  44 
Systems,  Description  of.  .  439 
Three-Phase,  Definition  .  .  52 

Transposition     509 

Transposing,    Definitions    53 

Traveling   Waves    of   Potential.    394 

Treating  Cross-arms 690 

Tree    Guying     706 

Insulators    713 

Trimming     712 

Wire,   Circular  Loom   Cov- 
ered,  Specification  for.  .    259 
Wire,    Specification    for...    259 
Trigonometric    Functions,     Nat- 
ural;    Tables    of 85-91 


PAGE 

Trimming  Poles    681 

Triple       Braid,       Weatherproof 
Solid     Wire,     Diameters 

of    217 

Weatherproof  Wire,    Solid 

Weights    of    219 

Weatherproof    Wire, 

Stranded,    Diameters    of  218 
Weatherproof    Wire, 

Stranded,    Weights    of.  .    220 
Triple   Petticoat  Insulator,  Def- 
inition          53 

Tubular   Poles,    Steel,    Table...    146 

Steel   Poles    147 

Steel  Poles,   Use   of 147 

Two-Phase,   Definition    53 

System,    Definition    of.  ...    443 
Five-Wire  System,  Descrip- 
tion         445 

Four-Wire       System,       De- 
scription         445 

Four-Wire    System,    Vector 

Diagram     455 

System,        Calculation       of 

Regulator    Capacity    .  .  .    503 
System,        Regulation       of 

Regulators     502 

Three-Wire   System,   Calcu- 
lation  of    477 

Three-Wire      System,      De- 
scription   of     443 

Three-Wire    System  Vector 

Diagram     456 

Two-Wire    Direct    Current    Sys- 
tem,  Description   of.  ...    439 

Mains,    Definition    53 

Single-Phase     System,     De- 
scription   of     443 

System,      Direct      Current, 

Method  of  Calculating.  .    464 
Types   of  Loads,   Power-Factors 

of      505 

Metal    Pins     .  .  .274-278 


u 

Units,     Electrostatic     Capacity, 

Definition     9 

Electrostatic,   Definition    .  .      20 

Fundamental     102-104 

Heat,   Definition    31 

Magnetic,    Definition    ....      38 

Metric      103-104 

of   Resistance    189 

Resistance,    Comparison    of  189 

Use   of  Tubular  Steel  Poles...    147 


Various  Types  of  Loads,  Power- 
Factors    of     505 

Varnish,    Insulating,    Definition      34 

Vectors     451 

Additions 454 


[816] 


INDEX 


PAGE 

Vectors,  Analysis,  Scott  Trans- 
formation    378 

Description    of    452 

Diagrams     451 

Diagram,    Definition     ....  53 
Diagrams,        Single  -  Phase 

Transmission      454 

Diagram,  Three-Phase  Sys- 
tem       457 

Diagram,  Two-Phase,  Four- 
Wire    System     455 

Diagram,      Two-Phase, 

Three-Wire    System    ...  456 

Plane,    Definition    43 

Quantity,  Definition    .....  53 

Sum,    Definition    53 

Velocity,      Angular,      Definition 

of 5 

Vibration    of    Wave,    Amplitude 

of    5 

Volt,  Definition 54 

Volt-Ampere,    Definition 59 

Voltage  Distribution,  Wet  Arc- 
over,  Suspension  Insula- 
tors    311 

Distribution,        Suspension 

Insulators    302 

Distribution,   Dry    Arc-over 

Suspension    Insulators.  .  311 

Drop   of,    Definition 18 

Regulator     501 

Terminal,  Definition 51 

on      Transmission      Lines, 

Choice    of    484 

Voltmeter,    Iron    Loss 356 

Vulcanizing  Rubber 182 

w 

Washers 279 

Specification    for 279-281 

Water-Gas-Tar,    Creosote    592 

Production  of 592 

Specification    of    629 

Water  Pipe  Grounds 433 

Watt,    Definition     55 

Watt-Hour,    Definition    55 

Wattless  Component  of  Electro- 
motive-Force,   Definition     ...  55 
Wave,    Complete,    Definition...  11 

Electric,    Definition     55 

Waves,    Traveling     394 

Weather  Map    756 

Interpretation    of    758 

Symbols 755 

Weatherproof    Insulation     ....  181 

Insulation,    Definition     ...  55 

Wire,    Definition     55 

Weight  of  Conductors,  Elec- 
trical System,  Compara- 
tive    450 

of  Wires,   Stranded,   Table 

of 220 

of  Wire,   Solid,  Table  of..  219 


PAGE 

Weight  of  Wire  and  Ice,  For- 
mulae for  527 

Wellhouse     Process      of     Wood 

Preservation    600 

Western    Cedar    Poles,    Dimen- 
sions   of     130 

Specifications   for    129 

Western     Red     Cedar,     Absorp- 
tion of  Creosote    662 

Fire  Killed  Poles 117 

Logging   of    114 

Tank  Treatment  with  Cre- 
osote         661 

Time  of  Cutting 116 

Where  Grown 114 

Western    Yellow    Pine,    Annual 
Service     Charge,     Wood 

Preservation    660 

Comparative  Cost  of  Treat- 
ment         661 

Logging   of    119 

Time    of    Cutting 121 

Treated  with  Creosote.  .  .  .    656 
Treated  with  Crude  Petro- 
leum         658 

Treated     with    Zinc     Chlo- 
ride        659 

Where    Grown     119 

Western     White     Cedar     Poles, 

Dimensions    of    130 

Specification    for     129 

Wet  and  Dry  Process,  Porce- 
lain Insulators,  Relative  Ad- 
vantage of  292 

Wet  Process,  Porcelain  Insu- 
lators    291 

White     Cedar     Logging.  ..  .111,  112 

Time    of    Cutting Ill 

Where  Grown    Ill 

Wind   Pressure,    Formulas 523 

on  Wires,  Formula?  for...    527 

Wind   Shakes    124 

Velocities,    Table    for    Cor- 
recting       781 

Velocities,    Table   of    Maxi- 
mum Recorded 772 

Winding,    Concentric    323 

Interleaved    323 

Pancake     323 

Secondary,    Definition     ....    48 
Wire       Aluminum,        Stranded 

Bare,    Table   of   Loading.  .  .  .    541 
Wire       Aluminum,       Table       of 

Physical    Constants    .  .  .    185 
Aluminum       Weatherproof 
Insulated,      Specification 

for    257 

.Attached  to  Structure 711 

Bare  Aluminum,   Specifica- 
tion   for     257 

Bare   Copper,    Solid,    Table 

of  Loading    539 

Bare      Hard-Drawn      Cop- 
per, Specification  for    .  .    252 


[817] 


INDEX 


PAGE 
Wire,   Bimetallic,   Definition ...        7 

Braided,    Definition    7 

Breaking        Strength        of 

Solid,  Table  of 215 

Breaking  Strength  of 
Stranded,  Table  of....  216 

Cap,  Definition 8 

Capacity    of    Solid,     Table 

of 226 

Capacity       of       Stranded, 

Table  of 228 

Carrying    Capacity    of.  ...    722 
Charging  Current  of  Solid, 

Table    of    238 

Charging  Current  of 
Stranded,  Table  of.  ...  244 

Clearance     711 

Composite,    Definition     ...      11 
Copper,    Table    of   Physical 

Constants     184 

Copper,      Bare,      Stranded, 

Table  of  Loading 538 

Copper      Clad,      Table      of 

Physical  Constants   ....    186 
Copper,      Solid      Insulated, 

Table    of    Loading 540 

Copper,    Specifications    for 

Weatherproof,    Insulated  251 
Copper,    Table    of    Current 
Carrying  Capacity    ....    204 

Definition     55 

Diameter    of,    Solid,    Table 

of 217 

Diameter       of,       Stranded, 

Table    of 218 

Drawing     181 

Duplex,    Definition    18 

Gauge,  American,  Defini- 
tion of 4 

Gauge,  Micrometer,  Def- 
inition    38 

Gauges     195 

Gauges,    Comparison  of .  .  .    195 

Guy,    Definition     25 

Guy 212,    701 

Hard-drawn  Copper,  Defi- 
nition    26 

Hard-Drawn,    Copper  Clad 

Steel,   Specifications  for.    254 
Inductive      Reactance      of 

Solid,  Table  of 229 

Inductive      Reactance      of 

Stranded,    Table    of 235 

Insulated,    Definition    ....      34 

Insulation 711 

Iron,  Table  Physical  Con- 
stants    188 

Live,    Definition    37 

Location    on    Pole 722 

Manufacture  of,  Applica- 
tion of  Rubber  Com- 
pound    182 

Manufacture  of,  Protection 
of  Rubber  Insulation  .  .  183 


PAGE 
Wire    Manufacture    of,    Rubber 

Insulation    181 

Manufacture        of,        Vul- 
canizing       182 

Manufacture    of,    Weather- 
proof Insulation 181 

Manufacture        of,        Wire 

Drawing 181 

Manufacture       of,       Work- 
ing Ingots 181 

Materials,    Table    of    Prop- 
erties        537 

Percentage        Conductivity 

of,    Definition    41 

Positive,    Definition    44 

.  .Reinforcing   of    721 

Resistance   of   Solid,   Table 

of     221 

Resistance   of   Stranded...    222 
Rubber      Insulated,      Tree, 

Specification  for    259 

Running  Through  Trees.  .    713 
Self-Induction  of  Stranded, 

Table    of    225 

Sizes  to  Be  Used 709 

Solid,     Self-induction, 

Table   of    223 

Splicing 715 

Steel,     Table     of     Physical 

Constants     187 

Stranded     Steel,     Loading 

of 536 

Strands    197 

Stringing    of    Secondary.  .    729 

Support   of 711 

Tables     184 

Tie    714 

Weatherproof,   Definition .  .      55 
Weights    of,     Solid,    Table 

of 219 

Weights       of,        Stranded, 

Table   of    220 

Wiring  of  Corner   Poles 720 

of    Poles    720 

Wood  Creosote    594 

Cross-Arms    267 

Cross-Arms,       Specification 

of 267 

Decay  of    583 

Heart     582 

Insulator     Pin,      Specifica- 
tion   for    272,   273 

and  Metal   Pins 274 

Pins    270-272 

Poles 111-135 

Pole    Defects     123 

Pole   Specifications    125 

Porcelain    and   Metal    Pins  274 

Wood    Preservation 561 

Absorption  Results 660 

Alternate     Hot     and     Cold 

Treatment    605 

Analysis     Specification 
Water-Gas-Tar     Creosote   630 


[  818  ] 


INDEX 


PAGE 
Wood     Preservation,     Auxiliary 

Specifications     630 

B  r  us  h      Combined      with 

Open  Tank    610 

Brush  Treatment  ...608,  650 
Choice  of  Preservatives.  .  619 
Comparative  Costs  of 

Treatment    661 

Hot  Treatment    602 

Jacket  or  Butt  Settings.  .  610 
Low  Artificial  Pressure 

System     607 

with    Oils     586 

Open     Tank     Plants,     De- 
scription of 641 

Open     Tank     Pole     Treat- 
ments,   Western    Yellow 

Pine     655 

Open  Tank  Treatment.  .  .  607 
Open  Tank  Treatment  of 

Pole    Butts    640 

Petroleum  Oil 594 

Plants     597 

Process  for    596 

Specification     for    Analysis 

of    Mixed    Oils 629 

Specification     C  o  a  1  -  T  a  r 

Creosote     621 

Specification      for      Mixed 
Oils 


628 
633 


Specification  for  Oil  for 
Brush  Treatment  

Specification  of  Water- 
Gas-Tar  Creosote  629 

Steeping  in  Cold  Preserva- 
tives    602 

Western  Red  Cedar 661 


PAOE 

Wood     Preservation,     Western 
Red       Cedar,       Creosote 
and  Zinc   Choloride .  .  .  .    664 
Western  Red  Cedar,  Crude 

Petroleum    663 

Western    Red    Cedar,    Zinc 

Chloride 663 

Wood   Preservative   Agents.  .  .  .    585 
Analysis    Specification, 

Coal-Tar-Creosote    624 

Coal-Tar-Creosote    587 

Comparison   of    664 

Salts 594 

Water-Gas-Tar  Creosote    .  .    592 

Wood   Creosote 594 

Wood,    Sap    582 

Structure  of    578 

Work,    Definition    55 

Working   Ingots    181 


Y-Connector,   Definition    56 

Y-Current,    Definition     56 

Y  and    "A"    Transformer   Con- 
nections,   Comparison    of.  ...  450 
Yellow      Pine      Poles,      Dimen- 
sions   of     133 

Specification    for     133 

Specification       for       Creo- 

soted    134 


Zinc,    Definition    56 

Plating,   Definition    57 


[819] 


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